Characteristics of living things
Organismims tend to be complex and highly organized. Living organisms can take energy
from the environment and change from one form to another. Organisms tend to be
homeostatic, they regulate their body and other internal structures. Living creatures
respond to stimuli. Living things reproduce themselves by making copies of themselves.
Life adapts and evolves in step with external changes in environment.
A tour of the cell
To study cells, you must have a microscope, Anthony van leuwenhook made the
microscope. Robert hooke was the first person to describe the cell. Both at royal society
in London u.k. miscroscopes evolved and there are many ways to look at things with
different microscopes. The light microscopes resolution is about 0.2 microns (size of
small bacteria) it is only 1000x magnification. In the 50’s the electron microscope was
made that allowed us to see inside cells to see much more like DNA and viruses, but cells
must be dead for this.
In slide ten the tope left and bottom right a cross section images of cells. And the other
two are surface images of cells.
Nanometers are much smaller than microns.
Take cells apart to study their components, centrifuge is used to fractionate (take apart)
and separate their major organelles.
The centrifuge spins cell and tears it apart. Low speed will fet the nuclei and the faster
you go the more stuff you get.
Simplest collection of live matter. Lowest hierarchical level that is alive. Basic unit of
life. It performs all functions needed to live and function.
Virus: occur in every organism. Some wreck havoc, other cause no disease or sign of
outward presence. Often highly specific to host and can only reproduce in a host cell.
They are rod shaped and they can not reproduce on their own.
2 basic types of cells. Eukaryotic and prokaryotic
prokaryotic, no nucleus, before nucles. Visible parts are plasma membreane, ribosomes,
cytoplasm and it may have a cell wall, pili, flagella and mesosomes. Plasma membrane
determines what gets in, it is like a bag of jello.
Bacteria range in size from as small as the largest virus to large enough for single cells to
be seen by the eye, they are the oldest known organism on earth. Eukaryotic cells have nucleus., they are in our bodies, Protista, fungi, plants and animals.
Protists are single cell eukaryotes in lakes and swamps. They have a true nucleus (nuclear
membrane with DNA). It has a plasma membrane, cytoplasm, nucleus, ribosomes,
organelles, endomembrane system, cytoskeleton and it may have a cell wall, matrix,
some organelles and flagella.
The nucleus, it is usually the iggeset organelle. Most genes in a eukaryotic cell in the
nucleus. Some are in the mitochondria. It averages about 5 microns I diameter. It is
sperated from the cytoplasm by a double membrane. They are separated by 2040
nanometers. Where the double membranes are fused, a pore allows large macromolecules
and particles to pass through. These pores are called lamina, hels send nudtrients and info
in and out, it controls what gets in znd out. robsomes may be on the nuclear wall, but
Chromatin is true genetic material in the nucleus, it is organized DNA, it is a diffuse
mass. Every species has a different amount and size of chromosomes and the cell splits
chromatin into chromosomes. The nucleuolus has no membrane, it makes the subunits of
ribosomes, rRNA is made with proteins to make ribosomal subunits. The nucleus directs
protein synthesis by making mRNA.
Cytoplasm, it is the stuff between plasma membrane and nuclear envelope, it has a
variable viscosity, main chemical is a water which is 80 percent and the rest is sugars.
Ribosomes, they are responsible for protein synthesis, contains rRNA, makes proteins
with 2 subunits.
Endoplasmic Reticulum, there is the rough and smooth, rough is studed with ribosomes
and they are the major component of cells running through everywhere. Cell that make
large numbers of proteins have lots of ribosomes in the nuclei. Free ribosomes are
ribosomes that are suspeneded int eh cytosol and synthesize proteins that function within
the cytosol. Bound ribosomes are attached to the outside if the ER. Ribosomes can shift
The endomembrane system, many of the internal membranes in a eukaryotic cell are part
of the enomembrane system. These membranes are either in direct contact or connected
via transfer of vesicles, sacs of membrane. The endomembrane system includes the
nuclear envelope, er, golgi apparatus, lysosomes, vacuoles and the plasma membrane.
Smooth er, loaded with enzymes and can make lipids and phospholipids, steroids and
oils. It catalyzesreactions with glucose, has many functions. Can also detoxify many
things in cells. Muscle cells have special smooth er for pumping calcium.
Rough er, it is the membrane and protein factory. It is especially abundant in those cells
that secrete proteins are packages in transport vesicles that carry them to their next stage.
It is also a membrane factory, membrane bound proteins are synthesized directly into the
membrane, enzymes in the rough er also eynthesize phospholipids from precursors in the
cytosol. As the er membrane expands, parts can be transferred as transport vesicles to
other compnents of the endomembrane system. All cells have different shapes and sizes from one another and their different shapes are
based on their individual functions. Some body cells have multi nuclei like muscle cells,
they work faster with brain signals.
Golgi, transport vesicles from er go to the golgi for modifications of the contents. It is the
center of manufacturing, warehousing, sorting and shipping. Extensive in cells
specialized fot secretions like liver cells. It is made of flattened membranes or saces tha
are 2 sides. The cis and trans. The cis is receiving and trans is the side vescicles leave.
During their first transit from cis to trans pole, products from the er are modified to reach
their final state. It can manufacture its own macromolecules, including pectin and other
noncellulose polysaccharides. Tags, sorts and packages materials into transport
Lysosomes are membrane bound sacs that contain enzyes that digestrs macromolecuels.
These enzymes hydrolyze proteins, fats, polysaccharides and nucleic acids. The enzymes
wprk best at pH 5. Proteins in the lysosomal membrane pump hydrogen ions from the
cytosol I the lumen of the lysosomes. Rupturing one or a few lysosomes has little impact
on a cell. Massive leakage from lysosomes can destroy a cell and this is autodigestion.
Lysosomes can fuse with food vacuoles, formed when a food item is brought into the cell
by phagocytosis. Lysosomes can also fuse with another organelle or part of the cytosol.
The recycling, this process of autophagy renews the cell.
Vacuoles, vesicles which are microbodies and vacuoles are larger versions. They are
membrane bound sacs woth varied fnuctions. Food vacuole, from phagocytosis, fuse
woth lysosomes. Contractile vacuoles, found in fresh water protists, pump excess water
out of the cell. Central vacuoles are found in many mature plant cells.
Plant cell vacuole, the membrane surrounding the central vacuole, the tonoplast is
selective in its transport of solutes in to the the central vacuole. Functions stockpiling
proteins or inorganic ions, depositing metabolic byproducts, storing pigments and storing
defensive compounds against herbivores.
The endomembrane system plays a key role in the synthesis and hydrolosis of
macromolecules in the cell. The various components modeify macromolecules for their
Mitochondria and clorplasts are organelles that convert energy to forms that cells can use
for work. Mitochondria are the sites of cellular respiration, generating ATP from the
catabolism of sugars, fats, and other fuels in the presence of oxyen. Chloroplasts are
found in plants and eukaryotic algae, they are the site of photosynthesis. Humans get their
mitochondria from their mothers. Mitochondria are like bacteria. They divide and they
have their own DNA. They divide and grow on their own, and have lots of enzymes
present for ATP production, a cell cant generate a mitochondira so we get our
mitochondrias from our mothers,
The chloroplast has 2 surrounding membranes and inside there are the thylakoid
membranes. Proteins and pigments are this for energy making. Chloroplasts are different in every plant and cell. They are both dynamic structures and their shapes are all
Peroxisomes, they are vesicle like structures in both plants and animals. They are single
membrane bound compartment. Enzymes that transfer hydrogen from various substrtates
to oxygen. This produces h2o2 which is the converted form of h2o. they are made from
cytosol and not the endomembrane system.
They cytoskeleton is a network of fibres extending throughout the cytoplasm. It organizes
all the structures and activites in the cell. It offers mechanical support and maintains the
shape of the cell. The fibre act like a geodisc fome to stabilize a blance between opposing
foces. It is anchorage for many organelles and cytolsic enzymes. It is dynamic –
dismantling in one part and reassembling in another to change cell shape.
Microtubules are hollow tubes that are 25 nm in diameter and they are composed of the
protein called tubulin. It controls cell shape, cell mobility, chromosome movement and
organelle movement. It also acts as tracks that guide motor proteins carrying organelles to
Microfilaments are 2 inverted actin strands. They are 2 nm in diameter. They control cell
shape, muscle contraction, cytoplasmic streaming, cell motility and cell division.
Intermediate filaments are thick cables that range between 812 nm and they are made of
different proteins in the keratin family. Theya re anchorage of nucleus and organelles.
Centrosomes and centrioles
in many cells microtubules grow out of the centrosome (region located near the
within centrosome of animal cell are a pair of centrioles (9 sets of triplet microtubules
arranges in a ring) and not present in plant cells.
centrosome, in animal cells the centrosome has a pair of centrioles, each with nine triplets
of microtubules arranged ina ring.
cilia are motility organelles in the cell and they are shorter and more abundant than the
flagella, cilia works like the oars of a boat.
Flagella are similar but longer and they beat in an s shape to move something forward
like fungi and some protists have flagella. Inside the flagella there are groupings of
microtubules and a central core with special motor proteins that help work with the
moving of the flagella.
Dynein is the motor protein and grabs onto the microtubules and warps them and then
reseases the outer microtubules and through this it moves the flagella
Cilia and flagella have the same ultrastrcture. They are the core of microtubules sheathed
by the plasma membrane. There are nine doublets of microtubules arranged around a pair
at the center, the 9 + 2 patterm. Flexible wheels of protein connect outer doublets to each other and to the core. Outer doublets are also connected by motoe proetins. Anchored in
the cell by a basa body which is a centriole.
Muscle cells also depend on cytoskeletal structures, but this one uses actin filaments that
are arranged parallel and they have motor proteins and myosin. Thicker filamerntrs,
composed of a motor protein, myosin, interdigitate with the thineer actin fibres. Myosin
molecules walk along the actin filament, pulling stacks of actin fibres together and
shortning the cell.
Cytoplasm streaming, in plant cells actinmyosin interactions and solgel transformations
drive cytoplasm streaming. Chloroplasts are kept in movement through the cytoplasm
streaming. The chloroplasts are moving to get the max amount of sunlight.
Plant cell wall is much thicker than the plasma membrane. Its made of cellulose. And the
pectin is used in the cell wall to act as a glue and keep the cells together. Read abount
junctions from pages 4447 in the book.
Anchoring junctions aka desmosomes, they are 2 cells attached by intercellular filaments
and they rivet cells together. Tight junctions prevent materials from moving between cells
and they form a belt around cell which forms a seal. Gap junctions are intercellular
connections between animal cells and like plasmodesmata, small molecules can pass.
Divide and conquer or cell division.
What do all cells require to survive, they need to have genetic instructions and must
produce required molecules and it must direct life processes and this all come from the
dna in all cells. Cells divide for growth of the organism. Also to repair the organism. And
they divide for development of organ systems and all sorts of things in the organism.
The cell cycle are the activities of a cell from one cell diviosn to the next. The cell grows
adding more cytoplasm, the dna is replicated and the cell divides into two genetically
identical daughter cells.
The cell cycles transimtis a complete copy of genetic info aka dna and they transimt
materials necessary for cell to survue and use genetic info.
Prokaryotic cell. There is no nucleus but there is a nucleoid area but the genetic material
is in the cytoplasm and the are no membrane bound organelles like bacteria they divide
into binary fission and they just divide into two.
The prokaryotic chromosome is circular and the chromosome is replicatred. As it is
replicating the cell is elongating or growing and a new plasma membrane has to be added
and the plasma membrane then grows inward at the middle of the cell and then the parent
cell is divided in 2 identical daughter cells. Replication starts at appoint of origin. Once
the genetic info is divided they float away and a plasma membrane forms between them
and then they split. Ecoli can multiple every 20 minutes.
Eukaryotic cells are a little different Membrane bound organeslls including a nucleus and the dna is contained in the nucleus.
And exapmles of these cells and re fungi protest plants and animals and cells division of
somaic cells is called mitotic cell division ro mitosis. The eukaryotic chromosomes
cantains almost all the dna that is need to reproduce the same human. It has all the gentic
info. Mitochondira and chloroplasts also have some dna, but the divide differently than
Chromosome is eukaryotic cells are linear and long and get highly condensed in mitosis.
They are made of dna and protein. Protein is the structural component. The amount of
chromosomes varies with species. In humans we have 46 chromomes or strands. The
average length is about 4 cm. human cells have about 3 m of dna in them if they are
stretched out. all the dna in an adult can go to the sun and back if stretched out. chromatin
is the normal unbound up protein when the nuclear region disappears. When long stranda
of chromatin condense into choromomes. They are only called chromosemes when we
can see them. Read in the purple pages of the text f37 to f39. When the chromatin
condenses we see condensed chromosomes in an almost x shape.
Durting ther non division stage of mitosis. When the cells are doiuing their things the dna
is being extended and that’s when it is called chromatin. The cell can only read the cell
for instructions when it is chromatin. No instructions can come from chromosomes.
During cell division phase of cell cycle the dna molecules have to ccondense and it looks
like a bowl of spaghetti. By condesning the choromosomes it make it easier to move the
genetic info. Each chromosome is a single molecule of dna. This makes it easier to sort
and organize dna into daughter cells.
Mitotic division of somatic cells which are non reproductive cells in eukaryotic cells. A
single cell divides into two exact copies.
Ploidy. Organsims have a very specific number of sets in diploid and haploid cells. Poildy
referes to the number of pairs of chromomes in cells. Haploid is one copy of each
chromosome that is designated by small n. Diploid means that there are two copies of
each chromome. And it is represertned by 2n. humans are diploid.
Haploid means one set of chromosomes and diploid means two sets and triploid means 3
sets and plyploid is more than two complete sets. Many plants are polyploidy.
In the cell cycle there are two major phases. Interphase which is 3 stges and the dna is
uncondensed. Then there is mitotic cell division which is 5 stages and that’s when (fill in)
In g1 is the first gap in which organelles may replicate and the cell is growing and doing
its normal activities. S is the dna synthesis stage and the dna is replicated and production
of the proteins associated with cell division. This does not change the ploidy number. G2
is the stage where the cell has replicarted all the dna and ready to divide but it is still
doing normal stuff.
The cell cycle. In mitosis it happens much quicker than interphases. Cytokeniesis is the
division of the cytoplasm and sometimes this event doesn’t occur. By g2 each chromatin
is replicated but joined together at the centromemere and in mitosis they get ripped apart
at the centromere and then we wind up with two new cells with an exact pair of chromosomes. And the 2 daughter cells have the same number of chromasomes as the
Interphase is before mitosis and genetic material is called chromatin and dna preplication
occurs and the cell grows and does its thing. the nucleus is well defined, nucleoli is
present, centrosomes are replicated in animal cells only. Microtubules are extended from
the centrosomes and are called aster. Chromosomes have duplicated but not condensed.
Mitosis is prophase, prometaphase, methaphase, anaphase, telophase and cytokenisis
occurs in telophase if it does occur,
In prophase chromatin fibres become tightly coiled chromosomes,
Prometaphase nuclear envelope fragments, microtubules connect to chromosmes,
Metaphase the centrosomes are at opposite poles and the chromosomes ar metaphase
Anaphase begins when the paired centromeres separate, the chromosomes are halved and
move to opposite poles and move at centromeres first and the poles of the cells move
Read chapter 9 for Monday and do the quiz on Saturday.
Pre lecture quiz on Mendelian genetics due on Wednesday on chapter 10. We have an
online assignment that opens Friday at 9 am and closes Sunday and 11:59 pm. We will
have a pre lecture quiz on chromosomal genetics on chapter 11 due on Wednesday.
From last time, the end of mitosis. Read through page 166 to 170 and go through the
slides online. He was to lazy to teach the damn notes.
Cytokenisis is the process of splitting daughter cells apart, mitsos is the division of the
nucleus and cytokenisis is optional in plant cells. It is the pinching off in the middle of an
animal cell to make two animal cells. In plants they have that cell wall, but then they lay
down a cell plate that turns into a new cell wall between the two new cells. There is no
division in older plant cells.
Regulation of the cell cycle. Timing and rate of cell division in different parts of a plant
or animal are crucial to normal development. Skin cells divide regularly, liver cells divide
and so on. We need regulation so we don’t grow to be the size of dinosaurs. \
The distinct events eventds of the cell cycle are controlled by certain cell cycle control
system. These molecules trigger and coordinate key events in the cell cycle
these vent in the cell cycle. The control cycle is
controlled by a built in clock, but sometimes it can be
controlled by external and internal controls. The g1 checkpoint s the most important. If a cell receives
the go ahead it will complete the cell cycle and divide. If
it doesn’t the cell will switch into g0. G0 is a permanent
g1. It is when specialized cells stop reproduction to do
certain important functions, like nerve cells.
Internal and external clues. Kinetochores signal when y are
connected so anaphase finish copying notes later.
Meiosis. Haploiod is 1n. it is cells with one complete set
of chromomes. Sperms and unfertilized egg cells are
haploiud. When they fuze they make a zygote that is diploid
which is 2n. in an adult human cells there are 46 double
set of chromosomes. Diploid cells have homologous pairs.
Sexual versus asexual reproduction. Meisos is sexual
reproduction. The whole point of reproduction is
Asexual reproduction. It is very popular. These organisms
can do both asexual and sexual. An individual inherits all
its genes from one parent. The offspring are genetically
identical to the parent. One celled organisms divide. Hydra
budding, self pollinating flowers, some lizards, aphids,
aspens shoot up from roots and planarians pull themselves
apart. Genetic variation comes only from mutations and they
are given a greatly reduced ability to evolve due to this.
Recombination is a good way to get rid of bad genes, but
asexual is much faster.
Sexual reproduction. Each new individual gets half the
genetic info from one parent and the other half is from the
other parent. The offspring are genetically different from
the aprents. Sex makes much greater reproduction. Evolution
requires preexisting genetic variation. Sexual reproduction
provides much of the pre existing variation.
Life cycles. A diagramtic depiction of life is given under
neath of the events of an organisms development and
reproduction. Note where the ploidy levels and where in the
life cycles reproduction occurs. Animal life cycles have a
dominant diploid phase. Germ line cells under go meisis to
make a gamete cell.
In the picture of the chromosomes. There are two chromatids next to each other making a homologous pair of chromosomes.
Somatic cells have 23 pairs of chromomsomes. They are
homolougous which means two chromosmes of a given matched
pair. Each chromosome has many genes. Each gene occupies a
specific “locus” on a specific chromosome. Remember that
chromosomes are long linear strands of dna. Homologous
chromosomes have homologous genes at homologous loci. But
the two genes at the same location need to be identical.
Homologous chromosomes. Are the same size. The contain the
same gne loci, they may contain different alleles. A
diploid cell contains 2 sets of homologs which is 2n and
each set is from one parent.
The picture with two different coloured homoulogous pairs
shows how the same gene can be in a different form and each
of the lines represents a loci with a gene but there can be
many different versions of a gene.
Sex chromosomes. One pair of homologous chromosomes are
different. Human females have a true homoloug pair which is
xx. Males have xy. X and y are different, y has 13 known
genes and x has 179 known genes. X and y are called sex
chromomes. Autosomes= all other non sex chromomes.
Picture is a picture of an x with a y.
Phases of meiosis. Two successive nuclear divisions occur
in meiosis 1 which is reduction and meiosis 2 wich is the
division. Meisosis produces 4 haploid cells. And mitosis
produces 2 diploid cells. Meiosis 1 reduces the ploidy
level from 2n to n and meiosis 2 divides the remaining set
of chromosmes in a mitosis like process, most of the
differences in the process occur in meiosis 1. When the
arms of the chromosomes touch and switch between non sister
chromatids that is the actual genetic recombination part
and this only happens in meiosis 1.
Division inmeiosis 1 occurs in four phases: prophase,
metaphase, anaphase and telophase. During the preceding
interphase the chromosomes are prelicated to form siter
chromatids. They are generally identical and joined at the
centromere. Also the single centrosome is replicated. In
prophase 1 the chromosomes condense and homolous chromsomse
pair up to form tetrads. In a process called synapsis,
special proteins attach homolous chromosomses tightly
together. At several points the chromatids of homlougous chromsosmoes are crossed and segments are traded. A spindle
froms from each centrosome and spindle fibres attaché dto
kinetochores on the chromosome begin to move the tetrads
Multiple charismata are commonly found, in humans the
average number per tetrad is 2. The picture is a tetrad of
a grass hopper with 5 charismatas.
The next picture shows the crossing over section of meiosis.
At metaphase 1 the tetrads are arranged t the metaphase
plate. Microtubules from one pole are attached to the
kinetochore of one chromosome of each ter=trad while those
from the other pole are attached to the other. In anaphase
1 the homogous chromosmes separate and are pulled towards
In telophase1, movement of homologous (copy the rest of the
notes from the slides)
(fill in to independent assortment)
independent assortment is that there are 8 possible gametes
that could be made from 3 chromosomes. To find the answer
do 2 to the n. for thumans there is 2 to the 23 so there
are about 8 million possible combinations of chromosomes.
On its own I would create variablitity, but there is also
crossing over, which makes for more recombinanat cells. It
begins early in prophase 1. In humans crossing over can
occur between 2 to 3 times per chromosome pair. Also the
randowm nature of fertilization adds even more genetic
variation arising from meiosis. Any sperm can fuse with any
egg. The probability of making an exact person is 2 to the
23 times 2 to the 23 because there are 8 million in each
parent. The three sources of genetic variability is
independent assortment, crossing over and random
fertilization. Keep in mind that mutations are what create
a populations diversity of genes.
Asexually reproducing organisms are very rare because they
cant shuffle their genes and cant fix their genetic
problems. This is why they don’t last long.
Much of human history people didn’t now how heredity worked
and the greeks made their own weird theories. Anton van leuwenhook saw the first sperm and they made
weird concepts about how children were made and how blood
was passed on and what kind of traits are passed through
blood. The theories on how blood carries traits was
disproved by francis galton and gave two bunnies a blood
transfusion and they didn’t start showing each others
traits and they bot died.
Mendel was a monk who studied sciences and math and made
all his workings on genetics based on peas in his garden.
Peas are small and have few traits and they grow quickly,
and also work with things that work. Start with the simple
and then go to the complex. Also at that time there was a
bing interest in plants. He worked with 7 traits in the
peas. His methods were used to control fertilization. He
would use the pollen from one plant to fertilize the other
one and he wouldn’t allow for any self fertilization. True
breeding is when you cross it with itself and they always
come out the same. Hybridizing is the opposite. The true
breeding are the parent generation and then the first
hybrid offspring are the f1 and then the f1 self pollinated
and they made the f2 generation. Character is a heritable
featre and a trait is a variant of a character. monohybrid
cross is a cross that tracks the inheritance of a single
P gen is the parent generation. F1 is the first filial
generation forlowing the parents. F2 were the second filial
which were self pollinated f1’s. alleles are alternate
version of a gene. The dominant allele is the fully
expressed allele and the recessive allele is the allele
showing no noticeable effect.
The r f1 is all dominant genes and the the f2 has 2 colours
of seeds produced. He said that parents must contain two
copies of each gene and then the alleles segregate in
gametes which only contain one copy of each gene. Each f1
made two types of gametes. F2 can make 4 types of
genotypes. The model predicts a 3:1 phenotype. This was in
f1. Probabilities are only accur