BIOLOGY 1A03 Lecture Notes - Lecture 1: Sodium-Potassium Alloy, Atp Hydrolysis, Fructose
Theme 1 – Structure of Cell - Module 1 – Composition and Structure of Membranes
Unit 1 – Cells in our body
How many cells are in your body? 10 trillion as an adult
Each cell has the same genetic heritage as original fertilized cell
Cells differ in function, some are muscle cells, some are kidney, some are neurons etc.
Eukaryotic cells – have nucleus which has most genetic material
Prokaryotic cells – do not have a nucleus and DNA not organized in chromosomes
Bacteria often contain additional small circular molecules of DNA known as plasmids that carry a
few genes. They are commonly transferred between bacteria through the action of threadlike
structures known as pili which extend from one cell to another. Genes for antibiotic resistance
are commonly transferred this way which accounts for the quick spread of antibiotic resistance
among bacterial population. Structural support is provided by a cell wall made of peptidoglycan,
a complex polymer of sugars and amino acids.
We carry a lot of passengers who don’t share the same genetic heritage as us
o Eukaryotic cells – plant cells, fungi
o Prokaryotic cells – bacterial cells
o Most of these cells that we carry are harmless and are important parts of our body
We have 10 times as many bacterial cells compared to our own eukaryotic cells
Bacterial cells make up 2-3% of our body mass
Animal cell components
o Nucleus – is the storehouse for the cell’s genetic information and the site for RNA synthesis
o Mitochondria – produce most of the ATP that serves as the energy currency of the cell.
o Many cell membranes that define these organelles are associated with the protein
cytoskeleton that helps cells to maintain their shape and serves as a network of tracks for the
movement of substances within cells
o Plasma membrane – composed of phospholipids, proteins and regulates passage of
materials into and out of the cell
o Endoplasmic reticulum – involved in protein and lipid synthesis
o Lysosomes – degrade macromolecules
o Golgi apparatus – modifies and sorts proteins and lipids as they move to their final
destinations in or out of the cell
o Peroxisomes – break down specific organic molecules such as fatty acids and synthesize
other organic molecules such as cholesterol and some types of phospholipids
Plant cell components
o Cell wall – rigid barrier composed of polysaccharides
o Chloroplasts – enable plant cells to harness energy of sunlight to synthesize sugars
o Plasmodesmata – connect neighboring plant cells
o Vacuoles – organelles that contribute to the structural rigidity of plants by maintaining turgor
pressure against cell walls
Microbiome
A population of microbiotic organism (micro-organism or microbes)
Microorganism – organisms not visible under naked eye
Includes prokaryotic bacterial and small eukaryotic organisms
About 10000 distinct species of microbes on and in a healthy human body
Examples
o Streptococcus salivarious
Normal inhabitant of the upper respiratory tract and oral cavit
Member of a collection of bacteria that contribute to formation of dental plaque
One of the first microbes to colonize a germ-free newborn’s oral cavity abd gastrointestinal
tract
o Staphylococcus haemolyticus
Harmless on skin, pathogenic if it enters body
Infection leads to activation of immune system
o Bacteroides thetaiotaomicron
Predominant intestinal bacteria
Makes enzymes that are useful in breakdown of plant materials that we ingest. Examples –
oat fiber
No one has identified exact number of microbiomes living on our body, just an estimate
The bacteria Vibrio Fischeri are luminicent, capable of generating light. The squid use
their Vibrio-filled light organs like spotlights, projecting light downward to match light from the
surface as a way to camouflage themselves from would-be predators below.
The cow’s rumen (one of its four digestive chambers) contains microbes that break down the
cellulose in plant material. Without them, cattle wouldn’t be able to extract adequate nutrition
from the grass they graze.
Unit 2 – Phospholipids are the building blocks of membranes
Cell – a membrane bound structure containing macromolecules
4 classes of macromolecules
1) Nucleic acids (DNA & RNA)
Make up hereditary material of cell (flagellum in bacteria)
Found in DNA : chromosome/nucleoid
Information in DNA RNA eventually proteins
2) Proteins
Make up structural elements of cells (flagellium in bacteria)
Perform metabolic activities (ribosomes, enzymes)
3) Polysaccharides or Carbohydrates
Sources of stored energy
4) Phospholipids
Primary components of cell membrane
All cells are surrounded by membranes.
Membranes separate the internal and external environment. Allowing them to have their own
chemical compositions. Cell membranes are very thin.
Cell membranes are made up of lipid macromolecules.
o Each of these macromolecules has hydrophobic and hydrophilic properties that allow
"stacked" lipid bilayers to form.
o These lipid bilayers have a central "water-hating" hydrophobic core, and peripheral "water-
loving" hydrophilic surfaces.
doinhumolalala and 39849 others unlocked
9
BIOLOGY 1A03 Full Course Notes
Verified Note
9 documents
Document Summary
Theme 1 structure of cell - module 1 composition and structure of membranes. Each cell has the same genetic heritage as original fertilized cell. Cells differ in function, some are muscle cells, some are kidney, some are neurons etc. Eukaryotic cells have nucleus which has most genetic material. Prokaryotic cells do not have a nucleus and dna not organized in chromosomes. Bacteria often contain additional small circular molecules of dna known as plasmids that carry a few genes. They are commonly transferred between bacteria through the action of threadlike structures known as pili which extend from one cell to another. Genes for antibiotic resistance are commonly transferred this way which accounts for the quick spread of antibiotic resistance among bacterial population. Structural support is provided by a cell wall made of peptidoglycan, a complex polymer of sugars and amino acids. We have 10 times as many bacterial cells compared to our own eukaryotic cells.