All things Cells
Saron Hadgu
Louis Orisakwe
Victoria Ramos
Tiffany Tran
Prokaryotes vs. Eukaryotes
Prokaryotes:
● DNA concentrated
in nucleoid, which
is not membrane
enclosed
● no membrane
bound organelles
Eukaryotes:
● DNA concentrated
in membrane
enclosed nucleus
● larger volume
Prokaryotes & Eukaryotes Similarities
● bound by plasma membrane
● filled with semi-fluid jelly like substance
called cytoplasm
● contain chromosomes and DNA
● have ribosomes
Animal vs. Plant Eukaryote Cell
What animals have and plants don’t
Lysosome
Chloroplasts
Centrioles
Cell wall
- Flagella(loc. in some plant sperm)
What plants have and animals don’t
-
-Plasmodesmata-
Central vacuole and tonoplast
Controlling Internal Environment
Cell Membrane- selective barrier that allows passage of enough oxygen, nutrients and
waste to enter and exit the cell
Simple Diffusion- When an area of high concentration moves to an area of lower
concentration
Facilitated Diffusion- the movement of ions/molecules down its gradient across a
biological membrane with the help of a specific protein.
Active Transport- Movement of a substance moving against the membrane gradient
mediated by a certain kind of transport protein.
Hypo/Iso/Hyper
● Membrane
proteins-integral: used
in transport and as
receptors
-peripheral:
regulates ion channels
and receptors
Both are used as
transport channels or
as receptors
Cell receptorsglycoproteinhelp with cell to cell
recognition
Hydrophilic
-polar molecules
Hydrophobic
-nonpolar molecules
...therefore allows
small nonpolar
substances
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List of terms for cells that you need
to know
Endoplasmic Reticulum: combination of sacs and
tubes
Rough ERSmooth ER- synthesis of lipids,
Nucleus
Nuclear envelope-double membrane with pores;
located next to ER and enclose nucleus
Nucleolus- Multiple organelles that help make
ribosomes
Chromatin- made of DNA and protein and in a
dividing cell, individual chromosomes
Plasma membrane- enclose cell(in both plant and
animal cells)
Cell wall- enclose plant cell, gives shape, protects
cell and made of cellulose, protein, and other
polysaccharides
Ribosomes- Small circular organelles that produce
protein( bound to rough ER or nuclear envelope and
free in cytoplasm)
●
Golgi apparatus- organelle that modifies, sorting, and secretes
cell products
●
Lysosome- only in animals- hydrolyzes( digests
macromolecules)
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Mitochondria- contains a double membrane and ribosome;
where cellular respiration happens-ATP generated
●
Peroxisome-only in animals- produce hydrogen peroxide
through metabolic functions
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Microvilli- increase cell surface area; projection
●
Flagellum- made of microtubule and used for movement in
some animal cells
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Centrosome- where microtubules are made; spindle in mitosis
begins forming at two ends of centriole
-
Has centrioles in animal cells
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Cytoskeleton- provides cell shape and helps with movement
-
Microfilament, Intermediate Filament, Microtubules
●
Plasmodesmata- through cell walls connecting cytoplasm and
adjacent cells
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Chloroplast- organelle that converts energy from the sun to
chemical energy in sugars-photosynthetic-present in plant cells
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Central vacuole- used for storage, hydrolysis of
macromolecules, breakdown of waste; enlarges during plant
Protein Production
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Nucleus:
surrounded by nuclear envelope; envelope connected to ER
perforated by nuclear pores
function: contains chromosomes
contains nucleoli where ribosomal subunits are made
pores regulate entry/exit of materials
Ribosomes:
two subunits made of rRNA and proteins
function: protein synthesis
ER and vesicles:
membrane bound tubules and sacs continuous with the
nuclear envelope
functions: rough ER aids in synthesis of new proteins
Golgi Apparatus:
stacks of flattened membranous sacs
functions: modification of proteins which are then released by
vesicles
Energy Production
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mitochondria:
bounded by double membrane
inner membrane contains cristae
functions: cellular respiration
chloroplasts:
two membranes around fluid
stroma
contains thylakoids stacked into
grana
functions: photosynthesis
Cell Reproduction
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nucleus and DNA
(definition and function reviewed above)
centrioles:
involved in the development of spindle fibers in cell
division
Digestion
● lysosomes:
- membranous sac of hydrolytic
enzymes
- function: breakdown of
ingested substances,
macromolecules, and
damaged organelles
● vacuoles:
- membrane bound vesicle
- functions: digestion, storage,
waste disposal, protection
Cell Connections
● Connection Junctions
-Plasmodesmata- channels that connect
cells
-Gap Junctions-like plasmodesmata but
gap junction pores are not lined with the
membrane
● Barrier Junctions
-Tight Junctions- establish barriers that
prevent leakage of extracellular fluid
across layer of epithelial cells
-Desmosomes- fasten cells together in
strong sheets
Cell Division
Key terms:
CentriolesCentromereKineticoreMicrotubuleIntermediate FilamentsMicrofilaments-
Cell Regulation
● G1 and G2- chromosomes have 1
chromatid, prepares for cell division
● S phase- DNA replication
● cdKs- cyclin dependent kinases : a protein
kinase that is active when attached to a
cyclin
● cyclin- a protein that regulates cell cycle
DNA Replication
DNA Replication steps:
Helicase unwinds the DNA.
Single binding protein stabilizes the strands.
Leading strand is then synthesized by DNA pol 3 (5 to 3).
Primase sets RNA primer
DNA pol 3 puts DNA down creating okazaki fragments
DNA polymerase 1 removes primer and puts DNA
Ligase closes the gaps
Cell Communication
● Reception: target cell detects a signal
molecule from outside the cell
● Transduction: signal is converted to a form
that can induce a cellular response
● Response: specific response to signal
molecule
Cell Communication
cAMP
Protein
kinase
Cell Division
G protein
Energy Transformation
ATP- bonds between phosphates are unstable
ADP-ATP
energy coupling (exergonic to endergonic reactions)
-Phosphorylation can change shape of proteins
(conformational change)
Enzyme Function
Biological catalysts
-speed rate of reactions
-reduce activation energy
Induced fit ( fits like a key)
-temporarily bind to substrate
Affected by:
- temp
- ph
- salinity and concentration of substrate and enzyme-
Free Response- 2011 Form B
1. The cell cycle is fundamental to the reproduction of eukaryotic cells.
(a) Describe the phases of the cell cycle.
(b) Explain the role of THREE of the following in mitosis or cytokinesis.
" Kinetochores
" Microtubules
" Motor proteins
" Actin filaments
(c) Describe how the cell cycle is regulated and discuss ONE consequence of
abnormal regulation.
.(a) Describe the phases of the cell cycle.
(6 points maximum)
Correct order of cycle phases (1 point for entire correct list)
Interphase → Prophase → (Prometaphase) → Metaphase → Anaphase → Telophase → Cytokinesis OR
G1 → S → G2 → M
Correct description of at least one important structural or molecular characteristic of each phase (1 point each; 5 points
maximum)
• Interphase (including, if specified, G1, S, G2 subphases, correctly ordered): Chromatin dispersed in nucleus; nuclear envelope
and nucleoli are intact and functional; DNA is replicated here.
• G1, G2: Cell growth.
• S: DNA replication.
• Mitosis: Nuclear division.
• Prophase: Chromosomes begin to condense from chromatin; spindle apparatus assembled.
• (Prometaphase): Nuclear envelope disperses, nucleoli disperse, chromosomes connect to spindle apparatus fibers and begin to
show motility.
• Metaphase: Chromosomes reach maximum condensation and align on metaphase plate/plane.
• Anaphase: Two-chromatid chromosomes split into two daughter (one-chromatid) chromosomes; chromosomes move to opposite
poles of the spindle apparatus.
• Telophase: Chromosomes disperse back to chromatin form, nuclear envelope reassembles, nucleoli reassemble.
• Cytokinesis: If this occurs, it is normally coordinated with telophase; cell division.
b) Explain the role of THREE of the following in mitosis or cytokinesis.
(3 points maximum)
• Kinetochores
• Microtubules
• Motor proteins
• Actin filaments
Correct explanation of function (1 point each; if all four are chosen, only the first three are scored)
• Kinetochores: Located in centromeres of condensed chromosomes; microtubule attachment sites necessary for chromosome
positioning and movement.
• Microtubules: Fundamental structural element of the spindle apparatus; framework on which chromosome motility is generated;
define axis of division and cytokinesis.
• Motor proteins (correct location and function must be specified): In kinetochores, move chromosomes during mitosis, including
anaphase separation; involves kinesins and dyneins.
OR
In animal cell cleavage furrow, generate force to pinch cell in two; involves myosins.
• Actin filaments: Assemble under the membrane at the cytokinesis site; interact with myosin motor proteins to generate force to
pinch cell in two; also interact with astral microtubules of the spindle to position the spindle apparatus in the cell.
(c) Describe how the cell cycle is regulated and discuss ONE consequence of abnormal regulation.
(3 points maximum)
Regulation: Correct description of checkpoints, which block cell cycle progress unless specific molecular and/or
physical conditions are satisfied (1 point each; 2 points maximum)
• Action of MPF and CDKs in checkpoint regulation
• Contact inhibition of mitosis
• Hormones; growth factor control of cell cycle activity
Correct discussion of the consequences of abnormal cell cycle regulation (1 point maximum)
• Uncontrolled cell proliferation, as in cancer
• Apoptosis
• Non-disjunction/aneuploidy/broken chromosomes from abnormal spindle events
Enzyme Lab 1&2
The purpose of lab 1&2 was to determine the
effect ph has on the rate of an enzyme. It was
concluded that the specific enzyme thrives more in
a neutral environment rather than in an acidic or
alkaline environment.