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Midterm

Biology Midterm 1.docx


Department
Biology
Course Code
BIO 1140
Professor
Doug Johnson
Study Guide
Midterm

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Biology Midterm 1
Introduction to Cell Biology
A cell is:
- contains RNA and DNA (basic code
that controls the shape, size and
function of the cell and its offspring
as well)
- made up of organic molecules
- bounded by a membrane
- inside it contains cytosol (semi-
aqueous fluid, contained molecules)
- made up of a set of organic
molecules
cell theory was formalized by Schwann but
gave credit to Scleiden (first 2)
1. all organisms consists of one or more
cells
2. the cell is the basic unit of structure for
all organisms
3. all cells arise only from pre-existing cells
(ie. Basic unit of reproduction)
Diversity of cells:
- Shape often reflects function
- Cells that are capable of carrying out
all functions of life
- Others are specialized for a specific
task, and have to be supported
- Most are very small, but they can
vary in size (egglarge cell)(long
neutrons in giraffes)
- 200nm to 13 cm in diameter
Unity:
- All made up of proteins, carbs, lipids,
nucleic acids
- Fundamental chemistry is the same
- DNA is used for genetic information
across all cell types
- Metabolism: use of ATP as the
cellular energy currency
Units
-1µm = 10-6m
-1nm = 10-9m
Prokaryote are 1-5 µm and eukaryotes are 10 –
30 µm
Surface Area to Volume Ratio:
-SA: the rate of exchange of material
-Volume: determines the amount of
material required to keep up with all the
functions to keep the cell alive
-Relationship between how much
material is needed and how fast the cell
can get it
-As the cell get larger, this ratio is falling
-We can get larger organisms by dividing
into compartments each with their own
adequate conditions
-Elaborate the membranes to increase SA
Rates of diffusion:
-Time required for diffusion is
proportional to the distance squared
-Long diffusion distances, slower rate
(not enough to sustain life)
Adequate concentrations:
- As the cell gets larger, adequate
concentrations to keep the cell alive
increases
Prokaryote
- Staying small (1-5 µm)

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- Cytoplasm = cytosol + ribosomes,
organelles, etc
- Before nucleus
- Single circular chromosome
- One or more flagella
- Simple, living with the constraint of
staying small
- Enormous diversity
- Model prokaryote: E-coli (widely
used within biology to study different
aspects of prokaryote cells; easy to
grow; grows quickly; gut in most
mammals)
Eukaryote
- Difference in complexity within cell
membrane
oCollection of membranes
oGenetic material contained in
a membrane
oOther membrane bound
structures
- Presence of organelles allows it to
be larger
- Adequate concentrations in a
selective compartment
- Rather than diffusion, it uses
transport (ie. Motor proteins)
- Increase in membrane SA for faster
exchange
- Complexity in cytoplasm  can be
larger
- All require energy: much better at
using energy and generating it due
to the presence of mitochondria
(ETC
- Protists: single celled eukaryotic
organisms
- Multicellular: fungi, animals and
plants
- Model eukaryotes:
oSaccharomyces cerevisiae:
yeast
oArabidopsis thaliana: weed
(family of the mustard family),
grows in a petri dish
oCaenorhabditis elegans:
round worm, show age,
grows in a petri dish
oDrosphila melanogaster:fruit
fly, knows a lot about it,
breeds quickly, genetic
differences, shows
phenotypes
oMus musculus: mouse,
biological research, breeds
quickly, 3 month generation
type

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oDanio reri: zebra fish,
developmental research
(optically clear eggs: egg to
larvae in 48 hours),
biomedical research (can
regenerate heart cells),
small, breed every morning
Endosymbiont theory:
- 2 broad lines of eukaryotes
- Proposed in 1905
- Mitochondria from incorporation of
aerobic prokaryote
- Evidence: fossil records
(prokaryotes before eukaryotes)
- Prokaryotes cells formed a symbiotic
relationship with aerobic bacteria
- 2nd event  chloroplast
(photosynthetic bacteria)
Mitochondria:
- Oxidative metabolism yielding ATP
- ~ 2µm
-Double membrane, cristae
-Circular mDNA; similar, simpler
ribosomes
-Reproduce by binary fission
-Inner membrane contains protein
complexes
-Inner membrane is prokaryotic
Chloroplast:
- Conversion of light energy to
chemical energy (complex
carbohydrates)
- ~5 µm
-Double membrane; thylakoids
-Circular cpDNA; smaller, simpler
ribosomes
-Reproduce by binary fission
-Inner membrane contains protein
complexes
-Inner membrane is prokaryotic
Evidence for origins of mitochondria and
chloroplasts
- Experiment: wheat mitochondria was
used
- Small ribosomal subunit were
sequenced
- Looked for similarities that were
greater than chance alone
- Prokaryote is higher than chance
alone
- For wheat is the same as predicted
by chance
- Shared an evolutionary history
Present day endosymbiosis (Elysia
chlorotica):
- Found photosynthetic algae on
animals
- Solar powered slug:
oUse photosynthesis for food
oEndosymbiotic relationship
whit chloroplasts
oWhen it feeds on algae, it
incorporates chloroplasts
with the cells in the gut
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