U7: F2 Cells Flashcards
1
Q
main building block of cell membranes
A
phospholipids
2
Q
components of phospholipids
A
- phosphate head
- glycerol backbone (holds fatty acid tails to phosphate heads)
- fatty acid tails
3
Q
the head of a phospholipid is
A
hydrophilic
4
Q
the tail of a phospholipid is
A
hydrophobic
5
Q
amphipathic means
A
molecule has a hydrophilic and hydrophobic part
6
Q
the inside of the phospholipid bilayer is
A
hydrophobic
7
Q
what can pass through the cell membrane?
A
small, nonpolar molecules pass quickly through passive diffusion (gases)
small, polar molecules pass through slowly (water, ethanol)
large, nonpolar molecules pass through slowly (benzene)
8
Q
what kinds of things do not pass through the cell membrane?
A
large, polar molecules (like glucose)
charged molecules (Na+, Cl-, amino acids)
9
Q
which conformation presents more kinks in the phospholipid membrane?
A
cis
10
Q
what 3 components make up the cell membrane?
A
phosopholipids, cholesterol, and proteins
11
Q
what makes cholesterol relatively stable?
A
multiple rings in the structure
12
Q
what is cholesterol’s role in the cell membrane relative to temperature?
A
when temperature is low - cholesterol helps increase fluidity
when temperature is high - cholesterol helps reduce fluidity
13
Q
what forms do proteins take in the cell membrane?
A
integral membrane proteins (embedded in cell membrane)
peripheral proteins (sit on top of membrane)
14
Q
what are the roles that proteins serve in the cell membrane?
A
can act as receptors or help transport molecules
15
Q
what molecule binds lipids or proteins?
A
carbohydrates
use the prefix glyco- to signify this (glycoproteins or glycolipids)
16
Q
fluid mosaic model
A
top view of the cell membrane that looks like a mosaic
called fluid because proteins and phospholipids can move around
17
Q
_____ comprise 75% of the cell membrane’s mass
A
proteins
18
Q
lipid bound protein
A
protein embedded in the intermembrane space and do not serve much of a purpose
19
Q
channel proteins
A
allow molecules, like ions, to pass into the cell without using any energy
ions flow DOWN concentration gradient (high to low)
20
Q
carrier proteins
A
carries substances into or out of the cell
can go AGAINST concentration gradient
uses energy/ATP
21
Q
glycoproteins are for
A
signaling (allows cells to recognize other cells)
22
Q
what 3 factors affect membrane fluidity?
A
- temperature
- cholesterol
- unsaturated vs saturated fatty acids
23
Q
fluidity of the membrane at low vs high temperature
A
low temp = low fluidity (phospholipids crystallized and packed)
high temp = high fluidity (phospholipids have gaps)
24
Q
how does cholesterol affect fluidity at high and low temperatures?
A
at low temperature, it inserts itself to increase distance between phospholipids to increase fluidity
at high temperature, it inserts itself to attract phospholipids and decrease fluidity
25
saturated vs unsaturated fatty acids effects on cell membrane fluidity
saturated (single bonds) -- lower fluidity (neat and tight)
unsaturated (double bonds) -- higher fluidity (bent nature causes distance between phospholipids)
26
transbilayer diffusion
phospholipid on outer leaflet moves to inner leaflet or vice versa
uncatalyzed, slow
27
lateral diffusion
phospholipid moves side to side
happens fast and often, uncatalyzed
28
catalyzed movement of phospholipids
both use ATP
flippase - flips from outer leaflet to the inside using protein catalyst called flippase
floppase - flips from inner leaflet to outter leaflet
scramblase (doesnt require ATP) - flips one to the inside and one to the outside at the same time quickly
29
potassium has a large concentration _______ the cell whereas sodium has a large concentration _______ the cell
inside; outside
30
primary active transport
directly uses ATP for energy to transport molecules
31
symport
both molecules move in the same direction into the cell
32
antiport
molecules move in different directions into and out of the cell
33
secondary active transport
energy is used indirectly to transport molecules into the cell (uses gradient already set up)
34
vesicle
small pocket of cell membrane that surrounds a molecule for transport
35
endocytosis
the ingestion of large particles and uptake of fluids or macromolecules in small vesicles
uses a lot of energy
36
exocytosis
a process by which the contents of a cell vacuole are released to the exterior through fusion of the vacuole membrane with the cell membrane
37
types of passive transport
diffusion
osmosis
facilitated diffusion
filtration
38
facilitated diffusion
protein channel binds target molecule and changes conformation to allow molecule inside the cell without an input of energy
39
solvent vs solute
solvent is what does the dissolving
solute is what is being dissolved
40
diffusion
spreading of molecules from high concentration areas to low concentration areas
41
hypertonic solution
more solute than solvent
42
hypotonic solution
more solvent than solute
43
osmosis
water as a solvent diffusing through a membrane from high concentration of water to low concentration of water
44
in exocytosis, what does the vesicle do?
merge with the cell membrane to release its contents
45
what molecules use exocytosis a lot?
neurotransmitters
46
phagocytosis
process where a cell binds to the item it wants to engulf on the cell surface and draws it inward while engulfing it
47
phagocytosis often happens in what context?
when immune cells are trying to destroy something like a virus or an infected cell
48
what are 4 common cell surface receptors that phagocytize?
opsonin receptors
scavenger receptors
toll like receptors
antibodies
49
opsonin receptors
used to bind bacteria or particles coated with immunoglobulin G antibodies by the immune system
50
scavenger receptors
bind to molecules produced by bacteria by recognizing the extracellular matrix of proteins that surround bacteria
51
toll-like receptors
bind to specific molecules produced by bacteria by binding to a bacterial pathogen to recognize bacteria and activate an immune response
52
antibodies
molecules that bind to specific antigens - molecules that act like a pathogen warning because they help alert the immune system
53
steps of phagocytosis (simple)
1. cell and virus come into contact with each other (accident, chemotaxis, cytokines)
2. virus binds to surface receptors on macrophage
3. use pseudopods to surround particle and enclose it in membrane
4. surrounded virus is enclosed in bubble like structure called phagosome in the cytoplasm
5. phagosome fuses with lysosome to become phagolysosome (breaks down virus)
6. phagolysosome lowers pH to break down virus
7. once contents have neutralized, phagolysosome forms residual body that contains waster products and discharges it from the cell
54
K+ inside (and outside) the cell are bound to
anions to neutralize the cell
(like proteins or Cl-)
55
what drives potassium out of the cell? what drives potassium into the cell?
out of the cell: concentration gradient
into the cell: membrane potential created when K+ leaves
56
when potassium moves out of the cell, what happens on the inside of the cell?
the anions are left behind and creates a negative charge inside the cell
57
what is the equilibrium potential for K+?
point at which K in = K out
~ -92 mV
58
tight junctions
connect cells with an impermeable layer
bladder, intestines, kidneys
59
desmosomes
connections that hold two cells together via the cytoskeleton but there is a space for ions and water to flow inbetween cells
intestines, skin
60
gap junction
two cells are connected by a tube like structure
allow ions and water to pass from cell to cell, also transmits action potentials
cardiac muscle and neurons
61
membrane receptors
integral protein that communicates with the outside environment
62
what kind of receptors do neurons use?
ligand gated ion channels
63
ligand gated ion channels
transmembrane ion channels that open or close in response to binding of a ligand
allosteric binding
64
what comprises the largest known class of membrane receptors?
G Protein coupled receptors (GPCR)
65
GPCR's have how many alpha helices?
7 transmembrane alpha helices
66
G protein
able to bind GTP and GDP, important for GPCR
67
all G proteins are
heterotrimeric (3 subunits)
68
subunits of G-protein
alpha, beta, gamma
69
what subunits of the g protein are attached to the cell membrane and how?
lipid anchors, alpha and gamma
70
GPCRs are inactive when
GDP is bound to the alpha subunit
71
the conformational change after ligand binding of GPCR causes the alpha subunit to
be attached to GTP instead of GDP, and separate itself from the other subunits
72
steps of GPCR ligand binding
1. ligand binds to GPCR
2. GPCR undergoes conformational change
3. alpha subunit exchanges GDP for GTP
4. alpha subunit dissociates and regulates target proteins
5. target protein relay signal via 2nd messenger
6. GTP hydrolyzed to GDP
73
example of GPCR in the body
epinepherine binds to GPCR (adrenergic receptor)
alpha subunit regulates adenylate cyclase, and turn ATP to cAMP
cAMP is the second messenger that increases heart rate, dilates blood vessels, and degrades glycogen to glucose
74
enzyme linked receptor
catalytic receptors
binding of a ligand triggers enzymatic activity of the receptor
75
what is a common example of an enzyme linked receptor
receptor tyrosine kinases (RTKs)
76
receptor tyrosine kinases
tyrosine is on the intracellular enzymatic portion
kinase transfers phosphate groups from ATP to intracellular proteins to activate them
77
RTKs occur
in pairs
78
after the ligand binds to RTKs,
the RTKs associate to form a cross-linked dimer
79
what happens when the cross-linked dimer is formed?
the tyrosines are phosphorylated because the association triggers kinase activity
cross-phosphorylation happens
80
after cross phosphorylation, what happens?
different proteins can come and attach themselves to the enzymatic portion of the receptor (intracellular)
81
the binding of proteins to RTKs can lead to
signal transduction and regulate gene transcription
82
RTKs are mostly known for
binding growth factors for cells
83
if someone's RTKs are dysfunctional, what can occur?
cell growth can be unregulated and lead to cancer or not grow at all
84
RTKs signal usually travels to the
nucleus
85
What are the defining characteristics of a eukaryotic cell vs a prokaryotic cell?
Eukaryotic cells are compartmentalised, contain organelles (membrane bound), have a nucleus, and divide by mitosis
86
How do prokaryotes replicate?
Binary fission (make two copies of everything in the cell and just divide into two)
87
Mitochondria
Organelle where cellular respiration occurs and energy is created
88
Endoplasmic reticulum
Continuous Folded compartment where protein synthesis occurs
mRNA is translated at the E.R.
89
Endoplasmic reticulum
Continuous Folded compartment where protein synthesis occurs
mRNA is translated at the E.R.
90
Golgi apparatus
Sends proteins to other parts of the cell (like secretion or to another organelle)
91
Lysosome
Environment inside lysosome is ve **
92
Peroxisome
Organelle that reduces reactive oxygen species into nontoxic forms
93
Where do proteins and mRNA enter or exit the nucleus?
Nuclear pores
94
Nucleolus
Center of the nucleus that contains very densely packed DNA where ribosome assembly occurs
Where ribosomal rna is assembled into a ribosome which is transported to the cytoplasm
95
Nucleolus
Center of the nucleus that contains very densely packed DNA where ribosome assembly occurs
Where ribosomal rna is assembled into a ribosome which is transported to the cytoplasm
96
The outer membrane of the nucleus is continuous with
The membranes of the endoplasmic reticulum (share interior space)
97
The outer membrane of the nucleus is continuous with
The membranes of the endoplasmic reticulum (share interior space)
98
Nuclear envelope
Refers to the combination of inner and outer membranes and nuclear pores that encloses the nucleus
99
Mitochondrial membranes
Outer membrane (permeable to smaller molecules)
Inner membrane (not permeable to small molecules
- includes lots of folds called Christa connected by Cristae junctions
100
The matrix of the mitochondria is located
Inside the inner membrane
101
Where does glycolysis occur?
Cytoplasm
102
Where does the PDC occur?
In the matrix
Pyruvate is converted to acetyl CoA
103
Where does the Krebs cycle occur? What about the ΕΤC?
Matrix
On the inner membrane
104
order of enzymes in the electron transport chain
NADH dehydrogenase
cytochrome Q (succinate dehydrogenase for FADH2)
cytochrome reductase
cytochrome C
cytochrome oxidase
105
while the electron transport chain is transferring electrons, what is happening at the same time?
ATP synthase funnels H+ into the cell to create concentration gradient while simultaneously pushing ADP and P together in an axel way
106
what is the main difference between the smooth and rough endoplasmic reticulum?
the rough ER has ribosomes, but the smooth does not
107
rough endoplasmic reticulum role(s)
site of protein synthesis
108
smooth endoplasmic reticulum role(s)
synthesizes lipids (cell membrane, steroids)
metabolizes carbohydrates
detoxifying drugs
109
what is the difference between proteins translated in the cytoplasm vs the rough ER?
cytoplasm: end in the nucleus, peroxisomes, cytoplasm, or nucleus
RER: secreted, become integral proteins in the cell membrane, end in ER, golgi apparatus, or lysosomes
110
post translational modifications happen in
the rough ER
111
secretory pathway
molecules that enter this pathway have a signal sequence detected in translation so that it gets pushed to the rough ER
goes from the ER-golgi apparatus to the lysosome or cell membrane
112
golgi apparatus role(s)
modifies proteins made in the RER
sorts and sends proteins to proper destination
synthesizes certain macromolecules for secretion
113
layers of the golgi apparatus
cis-stack (closest to ER)
medial stack
trans stack (furthest from ER)
114
where can proteins that use the secretory pathway end up?
in the lysosome (for recycling and breakdown)
the cell membrane for secretion or integration
115
lysosome role(s)
digest various molecules and substances via autophagy and crinophagy
116
autophagy
"self-eating"
lysosome digests molecules that part of the cell itself or other cells
ex: organelles that are no longer functional, macrophages of immune system
117
crinophagy
lysosome digests excess secretory products
ex: extra hormones that need to be broken down
118
after the lysosome breaks down molecules, what happens?
it releases the contents (building blocks/most basic parts) into the cytoplasm for reuse
119
what are the enzymes in the lysosomes?
acid hydrolases
(require acidic environment to function)
120
what is the environment inside the lysosome like? why?
acidic (~ 5)
safety mechanism for the cell - if it were to burst and the acid hydrolases escaped, the cell is about pH 7.2 so they will not function and the organelles will not get eaten
121
peroxisomes role(s)
lipid breakdown, detoxification
**protect cell from damage of peroxides - contains catalase which breaks down hydrogen peroxide into water and oxygen
122
what types of animal tissues are made from eukaryotic cells?
epithelial
connective
muscle
nervous
123
epithelial tissue
inner and outer lining
ex: outer layer of skin, outer and inner layer of organs, lines inside of cavities
124
endocrine and exocrine glands are made of
epithelial tissue
125
exocrine glands release their substances where?
directly to the target organ
126
endocrine glands release their substances where?
directly into the bloodstream, like hormones
127
forms of epithelial tissue
simple (one layer)
stratified (2+ layers)
128
where can you find simple epithelium?
places where substances need to diffuse from different places
ex: alveoli of the lungs to diffuse O2 and CO2
129
where can you find stratified epithelium?
in places that need to resist chemical or mechanical stress
ex: esophagus (acts as protective layer)
130
epithelial cells are attached to
basement membrane (made of fibers, like collagen)
131
is epithelial tissue vascular or avascular?
avascular
132
how do epithelial tissues get their nutrients?
via the basement membrane, which is semi-permeable
133
endothelium
epithelial lining of tissues like blood vessels and lymphatic vessels
134
connective tissues role(s)
support tissues
connects tissues
separates different tissues from each other
135
types of connective tissues
areolar
adipose
fibrous
blood
osseous
hyaline cartilage
136
examples of connective tissues
bone, cartilage, blood, lymph, adipose, membranes covering the brain and spinal cord
137
what are the characteristics of connective tissues?
cells, ground substance, fibers
matrix = ground substance + fibers
138
areolar tissue
binds different tissues together
provides flexibility and cushioning
139
adipose tissue
fat tissue
provides cusioning, stores energy
DOES NOT CONTAIN FIBERS
140
fibrous connective tissue
strong tissue that provides support and shock absorption for bones and organs
found in dermis, tendons, and ligaments
141
blood
no fibers
matrix = plasma
142
osseous tissue
bone tissue
osteocytes = cells
matrix = bone mineral / hydroxyapatite
143
hyaline cartilage
chondrocytes = cells
found in surfaces of joints
144
cytoskeleton role(s)
provides structural support
helps with movement
helps with transport of substances within the cell
145
the cytoskeleton is made of
microtubules, intermediate filaments, and microfilaments
(all made of protein)
146
microtubules
diameter of ~25nm
involved in mitotic spindle, make up cilia, make up flagella, help with transport of substances
147
intermediate filaments
diameter of ~10nm
provide structural support to the cell and help resist mechanical stress to help cell retain shape
like mattress springs
148
microfilaments
diameter ~7nm
help with movement of the entire cell from within (like cell division)
149
what are microfilaments made of?
actin, which joins to become an actin polymer, which combine to form actin filaments
150
how are microfilaments dynamic?
they can lengthen and shorten via actin polymerization and actin depolymerization, respectively
151
what are intermediate filaments made of?
made of several different proteins that twist to form filaments
152
what are microtubules made of?
alpha tubulin and beta tubulin dimers
153
what are microtubules bound to?
microtubule organizing center (MToc)
154
what are the different types of microtubule organizing centers?
centrosome
basal body
155
centrosome
organelle found near nucleus of the cell that contains 2 centrioles (rods)
156
centrioles are made up of
9 triplets
157
how many microtubules are required to make a centriole?
27 (9x3)
158
what are microtubules role in mitosis?
makes up mitotic spindle which connect to kinetichore fibers on the chromosomes
helps pull chromosomes apart to form 2 identical cells
159
what are basal bodies?
the MToc for cells that have cilia or flagella
160
what are basal bodies made of?
microtubules connected by nexin and dynein (use ATP)
- called the 9+2 arrangement because there are 9 pairs of microtubules surrounding 1 PAIR of microtubules
161
important function of microtubules
form network to connect soma to synaptic terminal of a neuron
162
what two proteins are found in neurons and help shuttle things down the microtubules?
kinesin and dynein
163
what kinds of things are shuttled down the microtubule path of the neuron?
synaptic vesicles that contain neurotransmitters proteins
lipids
organelles
164
kinesin and dynein can transport substances down the axon in which direction?
both directions
165
abiogenesis
theory that life formed from spontaneous generation
disproved by discovery of binary fission
166
cell theory major tenets
the cell is the basic unit of strucutre in life
all living organisms are composed of cells
all cells come from pre-existing cells
167
what were the first organisms to appear on earth?
archaea
168
types of extremophiles
thermophiles (heat)
halophiles (salt)
methanogens (swamp gas)
169
flagellin
makes up flagella of a bacteria
170
prokaryotes lack
membrane bound organelles (like nucleus or mitochondria)
171
bacterial chromosomes are made of
circular double stranded DNA
172
how do bacteria obtain nutrients?
from their enviroment using the flagella
173
bacterial shapes and names
sphere = coccus
bacillus = oval
spirochete = squiggle
174
the stain of bacteria is only located on
the outer layer of bacteria
175
what is the difference between gram positive and gram negative bacteria?
gram positive stays purple because the peptidoglycan layer is much larger in gram positive so it stays purple when wiped
176
steps of binary fission
origin of replication opens and replication begins
cell elongates & origins move towards cell ends as DNA is copied
septum forms down the middle
cell pinches in two
177
differences between DNA replication in bacteria vs eukaryotes
bacteria does not form mitotic spindles and replication occurs at the same time as dna separation, unlike mitosis
178
criteria for something to be "alive"
1. maintain homeostasis
2. different levels of organization
3. reproduction
4. growth
5. use energy
6. response to stimuli
7. adapt to environment
179
4 defining characteristics of viruses
1. size - very small
2. shape - capsid protein coat (can be icosahedral, helical, spherical)
3. nucleic acid (can be single stranded DNA or double stranded RNA)
4. type of host - obligate intracellular parasite (must utilize host cell to replicate)
180
how do bacteriophages inject themselves into bacteria?
complex shape with a head, sheath, and tail (injects like a needle)
181
how do viruses infect eukaryotic cells?
they utilize receptors on the eukaryotic cell membrane to trick them into letting them in via receptor mediated endocytosis
182
why do some viral cells contain an envelope?
gives them extra shape to be able to fuse into the cell membrane and inject the virus
"direct fusion"
183
3 ways that viruses inject themselves into cells
1. bacteriophage injection
2. no envelope: trick receptors into letting them in
3. envelope: directly fuse with membrane
184
lytic viral replication
DESTROYS cell
after virus infects host cell, virus replicates until cell breaks open to release virus into environment, and continues to create as many virus cells as possible
185
lysogenic viral replication
(provirus) virus is repressed in host cell in a dormant phase, and waits for bacteria to replicate with it in there until not repressed, so bacteria excises viral dna, which is then able to replicate and proceed to lyse the cell and continue on
186
retrovirus
enveloped ssRNA that contains 3 special proteins - reverse transcriptase, integrase, protease
187
steps of retrovirus
insertion of retrovirus
uncoating of envelope
reverse transcriptase create dsDNA
integrase creates sticky ends (cuts off 3' ends) and integrates viral DNA into nucleus of host cell
follows lysogenic pathway
protease cleaves to form mature viral cells
188
what about retroviruses is dangerous?
they are regularly transcribed with other DNA and do not have a dormant phase
189
subviral particles
smaller than virus
nonliving infectious agents
types: viroids and prions
190
viroids
single strand of circular RNA
catalytic RNA - can self cleave to create more viroids
ex: hepatitis D
191
prions
proteinaceous infectious particles
no genetic material, only made of proteins
made of beta sheets (normal proteins are made of alpha helix) = made of same proteins, different conformations
changes alpha helices to beta sheets
192
what phase do cells usually spend most of their time in?
interphase (growing phase)
*except cancer cells
193
what phase the cell actively divide?
mitosis
194
stages of interphase
G1(or to G0)
S
G2
195
G1 phase
growth phase that is the longest phase
most of cell's life
make organelles and proteins
196
G0 phase
branches off of G1 and is a phase where there is no more cell division
example: neurons
197
S phase
synthesis phase
dna replication where we go from 23 pairs to 36 pairs of chromosomes
198
G2 phase
growth phase where microtubules are made and the cell is prepared for mitosis
199
mitosis
process by which the cell divides
final stage of the cell cycle
products enter G1 phase and continue through cycle again or enter G0 phase
200
checkpoints of the cell cycle
between G1 & S
between G2 & M
201
what proteins regulate the cell cycle?
cyclin-dependent kinases (+ P group to (in)activate enzymes)
cyclin
202
what enzyme is always present in the cell?
CDKs (cyclin dependent kinases), but they are inactive
203
what is the role of cyclin in the cell?
specific cyclins are made at specific times in the cell cycle and this will ACTIVATE CDKs
204
what cyclins are made in the G1 phase?
cyclinD
cyclinE
205
what binds with cyclin D and cyclin E? where does this occur?
CDK2-E
CDK4-D
occurs at first checkpoint
206
what occurs at the first checkpoint?
CDK2-E and CDK4-D are formed
CDK4-D phosphorylates Rb protein to allow DNA replication to occur (Rb inhibits DNA replication)
207
what cyclin is made in the S phase? what does this bind to?
cyclin A
CDK2-A
208
what is CDK2-A responsible for?
activating DNA replication in the S phase
209
what cyclin is made in the G2 phase? what does it bind to? what is its purpose?
cyclin B
CDK1-B
activates mitosis
210
p53
"guardian of the genome"
binds DNA directly to produce proteins that block cell cycle progression
ex: p21 which inhibits CDK
211
Rb is produced from a
tumor suppressor gene
212
what occurs if the tumor-suppressor genes malfunction?
cancer
213
human diploid and human haploid
diploid = 46
haploid = 23
214
phases of mitosis
interphase
prophase
metaphase
anaphase
telophase
cytokinesis
215
interphase
formation of bivalent chromosome - dna strand of chromosome is copied and attached to the original strand at the centromere
216
prophase
centrosomes move to opposite ends
bivalent chromosomes pack into tight packages
mitotic spindle is formed
nuclear envelope dissolves
217
metaphase
each chromosome lines up in a single file line at the center of the cell
mitotic spindles attach to each chromatid
218
anaphase
mitotic spindles pry each chromatid apart and drag them to opposite ends of the cell
219
telophase
membranes form around the 2 new groups of chromosomes and the spindles are disassembled
at this point: there are 2 nuclear membranous groups of 46 chromosomes
220
cytokinesis
creates two clones of original cell
each with 46 monovalent chromosomes
221
sister chromatids are attached at
the centromere
222
what else is replicated in the S phase?
centrosome
223
where are centrioles located?
in the centrosomes
224
where do spindle fibers attach?
kinetochores
225
what is the main difference between mitosis and meiosis?
mitosis produces 2 diploid cells (2n)
meiosis produces 4 haploid cells (n)
mitosis = somatic cells
meiosis = gametes (sex cells)
226
germ cells can undergo
mitosis to produce more germ cells
meiosis to produce gametes
227
phases of meiosis (overview)
meiosis I: homologous pairs separated
meiosis II: sister chromatids separated
228
diploid number of germ cells
4
229
in each round of meiosis division, what stages occur?
prophase
metaphase
anaphase
telophase
230
prophase I
chromosomes condense and pair up with its homologue partner
crossing over occurs at this point
231
what assists sister chromatids with crossing over of homologues?
synaptonemal complex
232
chiasmata
cross shaped structure where homologues are linked after crossover
233
metaphase I
homologue pairs line up at metaphase plate
234
anaphase I
homologues separate to opposite ends of the cell
sister chromatids stay together
235
telophase I
newly formed cells are haploid and each chromosome has 2 non-identical sister chromatids
nuclear membranes begin to form again
unraveling
236
prophase II
starting cells are haploid cells from meiosis I
chromosomes condense
237
metaphase II
chromosomes line up at metaphase plate
238
anaphase II
sister chromatids separate to opposite ends of the cell
239
telophase II
unraveling
newly forming gametes are haploid, with each chromosomes containing just one chromatid
240
does meiosis always produce 4 gametes?
No
spermatogenesis usually generates 4 functional gametes
oogenesis usually only produces 1 functional egg cell because only 1 of the cells at the end of meiosis I proceed down egg cell pathway while the other becomes a polar body
241
what are the ways that meiosis "mixes and matches" genes
crossing over and random orientation of homologue pairs
242
what is a main difference between mitotic anaphase and meiosis anaphase I?
mitosis: sister chromatids are pulled apart
meiosis anaphase I: sister chromatids stay together, its the homologous PAIRS that get pulled apart
243
what is different between anaphase I and anaphase II?
the sister chromatids SPLIT in anaphase II
