Cell physiology Flashcards

1
Q

Animal cells – 3 compartments

A

1) cell membrane

2) cytoplasm

3) nucleus

protoplasm = cytoplasm + nucleus

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2
Q

functions of plasma membrane

A

1) barrier b/w cell & environment
(cells, ISF/plasma)

2) SELECTIVELY PERMEABLE MEMBRANE

3) I.e. UNIQUE internal cell environment

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3
Q

cell membrane structure

A

75% phospholipids

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4
Q

phospholipids are…

A

amphipathic

both polar and non-polar components

nonpolar fatty acid tails
polar phosphate head

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5
Q

cell membrane structure (bilayer)

A

high amounts of phospholipids in aqueous solution

= phospholipid bilayer

= phosphate heads towards water, FA tails away from water (towards each other)

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6
Q

majority of phospholipid bilayer is (hydrophilic? hydrophobic?)

A

hydrophobic (tails)

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7
Q

consequence of majority hydrophobic bilayer

A

only hydrophobic (non-polar) molecules can pass through

hydrophilic (polar) molecules need carrier/channel mediation

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8
Q

exception to what can/can’t typically pass through lipid bilayer

A

Size is important variable

some small polar molecules can pass through – even though polar

some large nonpolar molecules may need transport (?) – even though nonpolar

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9
Q

permeable to…

A

Non-polar, hydrophobic, uncharged, (small?) – E.G. STEROIDS, O2, CO2

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10
Q

impermeable to…

A

polar, hydrophilic, charged – E.G. IONS, LARGE PROTEINS

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11
Q

example of exception

A

H2O – permeable to some degree – even though POLAR, HYDROPHILIC

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12
Q

what happens if lose selective permeability?

A

cell would no longer be able to maintain homeostasis – would be destroyed

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13
Q

lipid bilayer is composed of which lipids?

A

75% phospholipids

20% cholesterol

5% glycolipids

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14
Q

cholesterol in the lipid bilayer

A

carries a (polar) OH group (HYDROXIL GROUP)

attaches to phosphate group (polar head)

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15
Q

function of cholesterol in lipid bilayer

A

structure @ high temp
fluidity @ low temp

1) maintains structure @ high temperatures

(by keeping phospholipids locked together)

2) maintains fluidity of membrane @ low temperatures

(Non-polar portion prevents phospholipids (tails?) interacting)

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16
Q

GLYCOLIPIDS in the lipid bilayer

A

sugar attached to lipid

FOUND ON EXTRACELLULAR SIDE

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17
Q

which side are glycolipids?

A

extracellular side

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18
Q

function of GLYCOLIPIDS in cell membrane

A

SIGNAL TRANSDUCTION (convert signal type)

CELL TO CELL ADHESION

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19
Q

what is GLYCOCALYX composed of?

A

“sugary coat”

composed of carbohydrate portion of glycolipids (& glycoproteins)

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20
Q

function of GLYCOCALYX

A

1) cell recognition/signalling

2) protection

3) regulates cell behaviour

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21
Q

Cell membrane PROTEIN categories

A

1) Integral proteins

2) Peripheral proteins

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22
Q

integral proteins

A

crosses bilayer (“embedded”)

contains both polar/nonpolar parts (AMPHIPATHIC?)

complex/large

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23
Q

peripheral proteins

A

on surface of membrane (external or internal side)

attach to polar head of phospholipid

or attach to integral proteins

less complex/large

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24
Q

membrane proteins functional types

A

1) Transporters

2) Ion Channels

3) Receptors

4) Enzymes

5) Linkers

6) Markers

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25
1) Transporters
INTEGRAL transports POLAR molecules E.g. GLUCOSE transporter AMINO ACID transporter
26
2) Ion Channels
INTEGRAL transports IONS can be... ONE WAY TWO WAY SINGLE ION MULTI ION
27
3) Receptors
INTEGRAL "lock & key" Takes specific LIGAND E.G INSULIN & IT'S RECEPTOR "ligare" -- to bind HORMONE IS LIGAND, BUT LIGAND NOT ALWAYS HORMONE Hormone = type of ligand
28
4) Enzymes
INTEGRAL OR PERIPHERAL Active side faces inside or outside cell Acts on SUBSTRATE 1) Breaks down SUBSTRATE --> products 2) CATALYZES REACTIONS (accelerate/cause) E.G. LACTASE protruding from EPITHELIAL cells of small intestine --> breaks down lactose
29
5) Linker
Integral or peripheral attach/link other proteins attach/link other cells STRUCTURAL STABILITY of membrane E.G. Blood clots via fibrinogen and platelets holds filaments inside/outside membrane
30
6) Markers
cell identity MAJOR HISTOCOMPATIBILITY PROTEINS MHC proteins --> ON OUTSIDE OF IMMUNE CELLS (e.g. macrophage) Display peptide fragment from PATHOGENS to T-cells for recognition
31
miscellaneous fact about drugs and membrane proteins
membrane proteins are target of over 60% of all drugs
32
Fluid mosaic model
fluid movement of phospholipids = membrane fluidity
33
cell types examples
nerve cell sperm cell egg cell skin muscle bone immune fat epithelial etc.
34
two types of transport
1) Passive transport 2) Active transport
35
passive transport does not require
energy, ATP uses potential energy
36
passive transport, where does energy come from?
electric gradient concentration gradient solutes move down gradient potential energy (gradient) becomes kinetic
37
how is membrane gradient created
selective permeability
38
resting membrane potential
neurons and muscle fibres facilitates Action Potentials (nerve impulse)
39
2 Types of Passive transport
1) Diffusion (solutes) 2) Osmosis (water)
40
Variables affecting Rate of Diffusion
1) Temperature 2) Surface area 3) Ratio of gradient 4) Size of particles 5) Thickness of membrane (distance)
41
2 types of Diffusion
1) Simple Diffusion (directly through membrane) 2) Facilitated Diffusion (transmembrane (integral) protein)
42
why facilitate diffusion?
larger, polar, hydrophilic/charged molecules e.g. Ions hormones drugs
43
Facilitated diffusion via.. A) (Ion) Channel protein or B) Carrier (transporter) protein
(ion) channel... DOES NOT CHANGE SHAPE OPENS OR CLOSES E.g. Calcium ion Potassium ion carrier (tranporter)... CHANGES SHAPE E.g. glucose fructose vitamins
44
gated channel protein
gate determines when ions can/can't flow in
45
types of gated Channel proteins (a type of facilitated diffusion, a type of passive transport)
LIGAND gate (ligand, e.g. hormone) VOLTAGE gate (voltage change) MECHANICAL gate (pressure)
46
Leak channels (in contrast to gated channels)
leak channels always open
47
OSMOSIS (passive transport)
water from high concentration to low When membrane impermeable to solutes Via membrane directly or Via AQUAPORINS (channel proteins for water) ("water pores")
48
OSMOTIC PRESSURE
minimum pressure that needs to be applied to SOLVENT to prevent it from passing into a solution VIA OSMOSIS measure of concentration of solution (?) I.e. pressure is directly proportional to concentration of solute Pressure is against SOLUTE-heavy (?) side (Pressure required to return to starting conditions)
49
ONCOTIC pressure
colloid osmotic pressure pressure in BLOOD PLASMA via proteins (E.g. ALBUMIN) ALBUMIN controls blood osmotic pressure --> prevents fluid leaking out of Blood Vessels PULL WATER BACK INTO VENOUS CIRCULATION
50
BCOP
Blood Colloid Osmotic Pressure
51
HYDROSTATIC PRESSURE
Pressure exerted by fluid on surroundings EQUILIBRIUM--> HYDROSTATIC PRESSURE = OSMOTIC PRESSURE in U-tube e.g. --> EQUILIBRIUM = UNEVEN WATER LEVELS
52
TONICITY & osmosis
CONCENTRATION of solutes in solution measures ability to change volume by changing water content HYPOTONIC solution ISOTONIC solution HYPERTONIC solution "hypertonic" EXTERNAL solution relative to INTERNAL cell environment
53
hypertonic solution
= cell shrinks "CRENATION"
54
hypotonic solution
= cell bulges (if beyond tolerated force, cell will rupture) "LYSIS"
55
Active transport
Sodium Potassium Pump
56
Sodium Potassium Pump -- which cell not found in
RBC
57
Sodium Potassium Pump -- function
maintains resting membrane potential (RMP) REMOVES 3 NA+ (ions) BRINGS 2 K+ (ions) Requires ATP
58
Sodium Potassium Pump establishes...
CONCENTRATION GRADIENT ELECTRICAL GRADIENT (i.e. RMP)
59
Concentration gradient via Na+K+ pump
more Na+ outside cell more K+ inside cell
60
Electrical gradient via Na+K+ pump
more positive outside cell more negative inside cell
61
RMP
every cell negative inside (negative RMP)
62
why negative RMP inside cell?
1) Na+K+ pump 2) more K+ (diffusion) channels (more permeable to K+ within cell 3) many negatively charged organic molecules inside cell (e.g. Proteins)
63
examples of RMP of various cells
neurons = -70mV skeletal muscles = -90mV smooth muscles = -60mV photoreceptor cells = -40mV RBC = -10mV
64
2 types of Active transport
Primary Active transport (via ATP) Secondary Active transport (via kinetic energy released by concentration gradient (passive movement) of other solutes)
65
example of primary active transport
Na+K+ pump
66
2 types of Secondary Active transport
Symporters (move 2 substances in same direction) Antiporters (2 substances in opposite direction)
67
Vesicular transport
Active (requires ATP) 1) ENDOCYTOSIS 2) EXOCYTOSIS
68
exocytosis
1) secretion of hormones E.g. insulin oxytocin 2) excretion of wastes E.g. Urea (kidneys)
69
endocytosis
1) phagocytosis 2) pinocytosis 3) receptor-mediated endocytosis
70
1) phagocytosis
eat large particles E.g. cells, bacteria, virus E.g. WBC, PSEUDOPODS monocyte macrophage neutrophil dendritic cells osteoclasts eosinophil
71
2) pinocytosis
bulk-phase endocytosis intake of fluid+solutes inside
72
function of pinocytosis
Controls cell volume transports molecules proves nutrients to cell via digestion of molecules (Via DIGESTIVE ENZYMES INSIDE VESICLE/lysosome)
73
receptor mediated endocytosis
selective endocytosis targets specific LIGANDS (ions/molecules) -- Via receptor proteins? receptor proteins recycled goes to endosome digested/destroyed in lysosome
74
TRANSCYTOSIS
combo of exocytosis and endocytosis e.g. antibodies cross placenta (endocytosis to cell of placenta exocytosis to other side toward fetus)
75
note terms:
phagosome pinosome lysosome endosome exosome
76
cytoplasm consists of
cytosol (fluid) organelles
77
cytosol % of cell volume
55%
78
cytosol % that is water
70-90%
79
list of organelles
Cytoskeleton Centrosome Cilia & flagella Ribosomes Endoplasmic reticulum Golgi complex Vesicles Mitochondria Nucleus Nucleolus
80
vacuole vs vesicle
Vacuoles are somewhat larger than vesicles, and the membrane of a vacuole does not fuse with the membranes of other cellular components
81
cytoskeleton 3 types
Microfilaments Intermediate filaments Microtubules
82
microfilament, intermediate filament, microtubule orientation (?)
microfilaments close to membrane (?) intermediate filaments in b/w (?) microtubules closest to centre (?)
83
Microfilaments (protein?)
smallest of 3 ACTIN protein usually near cell membrane
84
microfilaments functions
1) movement and support 2) Cytokinesis (cell division) 3) muscle contraction 4) connect cytoskeleton to integral proteins 5) form microvilli
85
intermediate filaments (protein?)
medium size protein KERATIN
86
intermediate filaments function
1) internal stability 2) organelles in specific position 3) bind adjacent cells (cell junctions)
87
microtubules
largest protein TUBULIN long/hollow made in CENTROSOME
88
microtubules functions
1) Cell’s shape 2) movement of organelles (e.g. vesicles) 3) movement of chromosomes during cell division 4) Cilia and the Flagellum (9 + 2 arrangement of microtubules)
89
centriole vs centrosome
A centriole is a barrel-shaped organelle which lives normally within the centrosome. Centrosomes are structures found inside of cells. They are made from two centrioles. Centrioles are microtubule rings. The main purpose of a centrosome is to organize microtubules and provide structure for the cell, as well as work to pull chromatids apart during cell division.
90
centrosome
Microtubule organize mitosis & meiosis (cell division) 2 centrosomes in each cell near the nucleus
91
centrosome consists of
Centrioles = a pair of cylindrical structures composed of 9 clusters of 3 microtubules
92
pericentriolar material
Pericentriolar material contains TUBULIN protein to help build microtubules Surrounds the centrioles and forms the starting point for mitotic spindles during mitosis
93
cilia
cilium singular 1) cell mobility (egg cells down the fallopian tubes) 2) sweep foreign particles along an epithelial lining (respiratory tract) MADE OF MICROTUBULES
94
flagella
flagellum singular propels cell forward only in sperm cells
95
ribosomes made of
made of... ribosomal proteins rRNA 50% protein 50% rRNA in eukaryotes
96
ribosome functions
protein synthesis (TRANSLATION) free-floating vs attached to ROUGH ER
97
free floating vs rough ER ribosomes function
floating = produce proteins for use in cytosol rough ER ribosomes = proteins for... A) organelles B) cell membrane C) exocytosis
98
ribosome composition
2 subunits of rRNA (Large unit and small unit) made in nucleus assembled in cytosol tiny granules under a microscope
99
ribosomes also found in...
mitochondria for ENZYME synthesis (one of SIX membrane protein types)
100
Endoplasmic reticulum
network of flattened sacs extend from nuclear membrane smooth ER (no ribosomes) rough ER
101
smooth ER function
lipid production phospholipids, cholesterol
102
smooth ER in liver cells...
detoxify drugs breaks down glycogen to glucose
103
smooth ER in muscle cells...
called SARCOPLASMIC RETICULUM stores/releases CA2+
104
rough ER
protein synthesis e.g. integral membrane proteins hormones structural proteins
105
rough ER continuous with...
nuclear membrane
106
proteins of rough ER exported via
"secretory pathways"
107
golgi complex
AKA golgi apparatus golgi body Receive/modify/transport proteins from the rough ER more complex/numerous Golgi body = larger secretory role.
108
golgi complex sacs
has 3 small sacs (cisternae): Entry/cis face = CONVEX = facing rough ER = receives protein via transport vesicles intermedias (medial) cisternae = protein becomes glycoproteins or lipoproteins (via ENZYME) Exit/trans face = concave side = releases product
109
vesicles
formed by a lipid bilayer separating contents from the cytoplasm or ECF
110
vesicles examples
Lysosome Peroxisome Secretory Vesicles
111
lysosome
digest substances (via enzymes) Acidic pH for optimal enzyme function --> pH <7 A) Autophagy : Removal of unnecessary or dysfunctional organelles B) Autolysis: self-digestion (destruction of entire cell)
112
autophagy
113
autolysis
114
peroxisome
breakdown of some organic molecules (very long FAs) Contains many digestive proteins peroxisomes neutralize H2O2 (hydrogrenperoxide -- byproduct of metabolism)
115
Secretory vesicles
to the plasma membrane for exocytosis e.g. proteins, hormones
116
mitochondria
ATP via aerobic metabolism (requires O2) via glucose, protein, lipids ---> ATP note gluconeogenesis
117
mitochondria more numerous in...
muscle and nerve cells (active)
118
mitochondria not present in...
RBC
119
mitochondria structure
Structure: outer and inner membrane CRISTAE (folds) of inner membrane between cristae is MATRIX = most reactions take place = Analogous with cytoplasm of the cell Contain ribosomes own set of DNA ability to self-replicate proteins
120
mitochondria DNA
DNA is different from the main set of chromosomes in the nucleus Only one “mitochondrial chromosome” many per mitochondria Much small than DNA in nucleus (?) Circular DNA (same as bacteria) Maternal inheritance only
121
mitochondria theory of origin
mitochondria are of bacterial origin
122
nucleus
“Brain” of cell responsible for... genetics protein synthesis (analogous to the CPU of a computer) The nucleus is where we find the DNA, our genetic material
123
found in nucleus
the DNA, our genetic material
124
how many nuclei?
Most cells have 1 nucleus (UNINUCLEATE) some have more (i.e. muscle cells) = (MULTINUCLEATE) some have NONE (i.e. mature red blood cells)
125
nucleus structure
NUCLEAR ENVELOPE = double membrane = separates from cytoplasm = like plasma membrane NUCLEAR PORES = substances in/out = Proteins/hormones in = RNA out
126
Nucleolus
largest structure in the nucleus spherical body made of clusters of RNA & protein Function is to make rRNA (ribosomes)
127
DNA
double stranded helix backbone of alternating pentose sugars and phosphate group complementary nitrogenous base pairs form hydrogen bonds
128
stretch out DNA in a cell DNA in body
would be 6 feet long would be 108 billion KM (150,000 round trips to moon)
129
genes
segments of DNA encode for traits codes for proteins that change structure/function/appearace
130
how many genes in human genome
20,000 genes less than 1/2 function is known
131
genes examples
124 genes for hair colour 16 genes for eye colour 4 genes for freckles
132
Allele
variation of DNA sequence at a GENOMIC location E.g. Allele for red hair Allele for blonde hair Allele for brown hair
133
Genotype
sequence of base pairs in gene "what genes say you should look like"
134
Phenotype
observable traits form genotype "what you look like"
135
Histones
protein balls DNA double helix coils around "
136
Nucleosome
combination of histone and DNA double helix
137
Linker DNA
section of DNA that links NUCLEOSOMES together
138
Chromatin
DNA/RNA/proteins prior to cell division scattered throughout nucleus before cell division granular mass when cell not dividing chromatin clusters --> forms chromosomes before cell division
139
groups of NUCLEOSOMES = chromatin (???) groups of CHROMATIN =chromatin fibre (???)
140
chromatin fibre
composed of chromatin section of many NUCLEOSOMES & Linker DNA
141
chromatin condensation
forms chromosome
142
chromosomes
arrangement of chromatin fibres during cell division
143
humans have...
46 chromosomes 23 from each parent
144
pairs of chromosomes =
HOMOLOGOUS CHROMOSOMES
145
AUTOSOMAL CHROMOSOMES
1-22
146
chromosome 23
SEX CHROMOSOME
147
SEX CHROMOSOME...
determines gender female = xx male = xy
148
CHROMATIDS
1/2 of chromosome 1 pair chromatid = chromosome
149
centromere
centre portion of chromosome holds two CHROMATIDS together (or 2 sister chromatids)
150
TELOMERES
non-coding terminal portion of chromosomes protects end of chromosome prevents genetic material loss when cell divides become short eventually --> Cell can't divide --> cell dies
151
short telomere
increased disease/aging
152
GENOME
total genetic info of organism carried in nucleus of cells
153
human genome project
2003 mapped out most of genome of human 20,000 genes took 13 years 2022 --> genome almost entirely mapped
154
number of genes correlation to intelligence
does NOT correlate with intelligence
155
PROTEIN SYNTHESIS
new proteins from genome ONLY IN CELLS W/ NUCLEUS No nucleus = no DNA = no protein synthesis E.g. RBC no nucleus PROTEIN SYNTHESIS begins in NUCLEUS, end in CYTOPLASM
156
protein synthesis 2 steps
1) Transcription DNA --> mRNA 2) Translation mRNA --> protein
157
Transcription (Protein Synthesis)
transcribing DNA into RNA all 3 types of RNA occurs in NUCLEUS
158
Transcription (RNA POLYMERASE)
RNA POLYMERASE @ PROMOTER REGION UNZIPS small section of DNA (two strands separated)
159
TEMPLATE STRAND CODING STRAND
template strand is transcribed coding strand is not complementary nucleotide bases are matched
160
on template strand, new nucleotides can only be added to which end?
3' (3 prime) end moves along strand in 3' to 5' (5 prime) direction
161
complementary nucleotide bases (nitrogenous bases)
e.g. A--> U (T replaced in RNA) G--> C T--> A C--> G
162
PROMOTER REGION CODING SEQUENCE TERMINATOR REGION
regions of gene RNA polymerase starts at PROMOTER ends at TERMINATOR region RNA polymerase then detaches from DNA & pre-mRNA molecule
163
SPLICING of pre-mRNA molecule (INTRONS and EXONS)
pre-mRNA molecule & snRNPs (Small Nuclear RiboNuclear Proteins) snRNPs splice pre-mRNA = moves non-coding segments (introns) = splices coding segments (exons) together
164
Alternative Splicing
same pre-mRNA molecule different mRNA strands different proteins snRNPs will splice a pre-mRNA strand differently at different times to produce different mRNA strands which are then translated to different proteins (from the same pre-mRNA molecule)
165
5' (5 prime) cap
modified guanine nucleotide 1) "REGULATION of nuclear export" 2) structural stability 3) improve translation
166
3' (3 prime) poly-A tail
adenine nucleotides 1) REGULATION of nuclear export 2) structural stability of mRNA 3) facilitate translation
167
where does mRNA go after?
after splicing & cap/tail --> pre-mRNA becomes mRNA --> EXITS NUCLEUS VIA NUCLEAR PORES goes to cytoplasm TRANSLATION OCCURS NEXT
168
Codon
three nucleotide (nitrogenous) bases each CODON in mRNA strand = Codes for specific AMINO ACID
169
start codon vs stop codon
start codon = translation initiates stop codon = translation stops
170
Translation
translating mRNA to polypeptide NUCLEIC ACID --> AMINO ACID performed by RIBOSOMES in CYTOPLASM
171
mRNA & Ribosome
mRNA attaches to SMALL ribosomal subunit (of 2) ANTICODON of INITIATOR tRNA binds to... CODON of mRNA (complementary bases)
172
tRNA
takes appropriate AMINO ACID to POLYPEPTIDE ANTICODON on tRNA binds to CODON of mRNA anticodon determines AMINO ACID
173
what happens after tRNA and mRNA connect?
LARGE RIBOSOMAL SUBUNIT attaches to SMALL SUBUNIT & mRNA Creates functional ribosome
174
functional ribosomes -- 3 binding sites (for tRNA + AA)
A site P site E site A site: binds tRNA carrying next amino acid ("acceptor" site) P site: binds initiator tRNA = tRNA carrying polypeptide chain E site: binds tRNA just before released from ribosome ("Exit" site)
175
A site after P site
anticodon of another tRNA + AA pairs with mRNA Codon (in A site) Peptide bond occurs between two AMINO ACIDS of two tRNAs di-peptide attaches to tRNA on A-site
176
shifting from A-site to P-site
Ribosome shifts both mRNA (and attached tRNAs) by ONE codon A-site becomes open again tRNA that enters E site EXITS
177
when does translation end?
When Ribosome reaches STOP Codon on mRNA protein detaches from final tRNA ribosomal subunits separate
178
which RNA types involved in TRANSLATION?
mRNA, tRNA also rRNA because ribosomes made of rRNA
179
what determines orders of AMINO ACIDS (& therefore structure of protein)
CODONS in mRNA (determined by DNA)
180
free vs attached ribosomes
free produce proteins for cell attached produce proteins for membrane, or exocytosis (Enter ER & sent to Golgi body for processing before wrapped by VESICLE)
181
POLYRIBOSOME (or POLYSOME)
multiple ribosomes TRANSLATING simultaneously Why? more proteins quicker more efficient (less mRNA)
182
2 types of cell division
1) MITOSIS exact replica for growth/repair 2) MEIOSIS creates gametes (sperm, ova)
183
diploid vs haploid
2 sets of chromosomes = 46 = 2n or diploid = n is number of distinct chromosomes 1 set of chromosomes = 23 = n or haploid nearly all cells have 46 chromosomes = 2 sets of 23 = one from each parent = diploid Gametes have 23 = sperm/ova = haploid
184
mitosis vs meiosis
mitosis: = diploid SOMATIC cells replicate = diploid becomes diploid meiosis: = diploid GERM cells replicate = produce GAMETES = diploid becomes haploid
185
cell cycle
cycle for mitosis/meiosis to occur
186
2 phases of cell cycle
1) INTERPHASE 2) MITOTIC PHASE (meiotic phase for meiosis) (meiosis goes through cell cycle twice)
187
mitosis
division of cell produces DAUGHTER CELLS occurs in SOMATIC CELLS occurs in GERM CELLS diploid --> diploid
188
mitosis and cell cycle
INTERPHASE duplicate material MITOSIS divide contents CYTOKINESIS 2 daughter cells separate
189
1) INTERPHASE (mitosis)
1) increase cell size 2) duplicate organelles 3) duplicate DNA
190
3 PHASES of INTERPHASE (mitosis)
G1 phase (growth 1) S phase (Synthesis) G2 phase
191
G1 PHASE of interphase (mitosis)
cell grow organelle duplicate CENTROSOME duplication begins (centrosome for division) Note cell is metabolically active
192
S PHASE of interphase (mitosis)
DNA duplicate (copy for each daughter cell) 1) DNA is unraveled via... DNA HELICASE 2) complementary strands made via... DNA POLYMERASE 3) = two identical copies of DNA I.E. 92 CHROMOSOMES
193
SISTER CHROMATIDS
I.E. 92 CHROMOSOMES(??? TYPO? SHOULD BE 92 *CHROMATIDS* INSTEAD?) identical duplicate chromosomes
194
G2 PHASE of interphase (mitosis)
growth proteins/enzymes made CENTROSOME duplication FINISHES ...
195
MITOTIC PHASE of mitosis
PMAT (Mitosis) + Cytokinesis = MITOTIC PHASE Prophase Metaphase Anaphase Telophase followed by CYTOKINESIS
196
(early) PROPHASE (PMAT) phase of Mitotic phase (of Cell cycle)
early prophase: CHROMATIN forms Chromosomes (via chromatin fibres) Sister chromatids join to form X via Centromere KINETOCHORE: protein that stabilizes Centromere REMINDER: (histone --> nucleosome --> Linker DNA --> Chromatin --> Chromatin fibre --> Chromosome)
197
(histone --> nucleosome --> Linker DNA --> Chromatin --> Chromatin fibre --> Chromosome)
198
KINETOCHORE
KINETOCHORE: protein that stabilizes Centromere
199
(late) PROPHASE
nuclear envelope breaks 2 pairs of Centrosomes go to opposite ends CENTRIOLES of centrosomes connect to CENTROMERES via... MITOTIC SPINDLES
200
MITOTIC SPINDLES
CENTRIOLES of centrosomes connect to CENTROMERES via...
201
2) METAPHASE phase of Mitotic phase (cell cycle)
chromosomes aligned on METAPHASE PLATE (aka equatorial plate) aligned in single line along middle of cell
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3) (early and late) ANAPHASE phase of mitotic phase (cell cycle)
early: centromeres split apart via MITOTIC SPINDLES pull towards Centrosomes sister chromatids pulled apart late anaphase: plasma membrane begins to separate = small CLEAVAGE FURROW
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4) TELOPHASE phase of mitotic phase (cell cycle)
Early telophase: CLEAVAGE FURROW grows larger --> chromatids at opposite ends (poles) Late telophase: separate NUCLEAR ENVELOPES form on each side
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Cytokinesis
plasma membrane forms separately around each DAUGHTER CELL cells move apart cell cycle / Mitosis complete
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Meiosis
division of single cell produce FOUR GAMETES germ cells to gametes diploid germ cells to haploid gametes
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meiosis differences from mitosis
meiosis cell division TWICE takes place in gonads (testes males, and ovaries females)
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interphase of meiosis
same as interphase for mitosis spermatogonia (precursor to sperm cell) ova cells 1) Increase in cell size 2) Duplication of organelles 3) Replication of DNA
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PMAT for meiosis (Prophase)
major difference b/w mitosis and meiosis: HOMOLOGOUS chromosomes join to form TETRAD
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tetrad and crossing over of chromosomes
"cross over" to exchange genetic materials crossing over creates genotypic diversity (GENETIC DIVERSITY)
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Prophase (Continued)
same as mitosis: nuclear envelope break centrosome move mitotic spindles
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metaphase
only difference is that TETRADS (not single chromosomes) line up same: on metaphase plate
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anaphase (meiosis)
sister chromatids stay together in meiosis (mitosis, sister chromatids pulled apart)
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telophase + cytokinesis
results in 2 gametes with haploid chromosome (1n = 23) have 23 chromosomes, but each have sister chromatid (?) 46 chromatids total --> 23 chromosomes 1/2 chromosome from each parent in mitosis --> 46 chromatids total --> 46 chromosomes (single chromatid)
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meiosis 2
two haploid daughter cells enter meiosis 2
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meiosis 2 PMAT
same prophase, but no TETRADS --> I.e. same as mitosis (?) METAPHASE 2 -- same as mitosis (?) ANAPHASE -- same as mitosis --> sister chromatids split TELOPHASE --> same as mitosis result = 4 gametes (23 chromosomes each, 23 chromatids) 4 gametes similar but not identical
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stem cells called germ cells
born with many stem cells (called GERM cells) they undergo MEIOSIS and form GAMETES
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what are the germ cells?
SPERMATOGONIA OOGONIA precursors to ova and sperm
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spermatogonia and oogonia, diploid or haploid?
diploid
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spermatocytes and primary oocytes
spermatogonia and oogonia create PRIMARY SPERMATOCYTES, and PRIMARY OOCYTES via... many rounds of MITOSIS these primary cells become sperm and ova via MEIOSIS
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spermatogonia --> Primary spermatocyte --> secondary spermatocyte --> spermatid --> mature sperm cell oogonia --> primary oocyte --> secondary oocyte --> mature ovum
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how do primary spermatocytes become sperm cells?
males at puberty --> increase in T primary spermatocytes enter MEIOSIS 1 & 2 results in SPERMATIDS
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SPERMIOGENESIS SPERMATOZOA
spermatid becomes spermatozoa via SPERMIOGENESIS
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Oogenesis
In females, mitosis of the oogonium is complete prior to birth Limited supply of primary oocytes About 2 million at birth, 400,000 by puberty The primary oocyte begins meiosis I in fetal development but it is arrested here until puberty Each month, 6-20 primary oocytes complete meiosis I and enter meiosis II These cells (usually only one) will finish meiosis II when and only if it is fertilized
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terms
While we are on the topic of gametes, let’s add in a few more terms that will pop up over the next few terms Gamete: sperm or ovum with with 23 chromosomes Zygote: is the union of 2 gametes (now 46 chromosomes) Blastocyst: The zygote will divide into 8 celled blastocyst that implants into the uterine wall