Cycle 2 Flashcards
What is the fundamental unit of life?
Cell
Microbiome are all ______ cells
Prokaryotic
T/F All the cells are sitting somewhere in the cell cycle
True
The phases of the cell cycle in meiosis
G0, G1, S, G2, or M are the phases of the cell
Mitosis in _____ cells
somatic
Meiosis in _____ cells
germ
___
Resting phase
Wait till receive a signal to replicate
Can also function in G0 (ex: neurons)
G0
___
Most cells function in G1
Preparatory phase (preparing for S)
Need a lot of energy
DIFFERENTIATION
In G1
___
Synthesis
Cells are undergoing DNA replication
Genome is doubled the copy
S
___
The period after DNA replicates
Cell prepares for division
G2
____
PMAT
M (mitosis)
T/F all cells replicate at all times
F: Not all cells replicate at all times, and not all replicate
During which phase of the cell cycle would you see the maximum amount of DNA in a cell?
Beginning of G2 phase (because S is finished)
During embryogenesis, you do not _____ and _____
G1 and G2 (no gap phases: goes from S to M)
Part of the complexity: the main part is ____ develops into us, from one cell to all these different tissue types
zygote
The process of one cell turning into different types of other cells is called _______
differentiation
The _____ is important because to become different types of cells, they need some time to think about which path they have to take
gap phase
______: Splits cells into two and make daughter cells
Cytokeneiss
Why do cells divide?
Multicellular growth (we are multicellular organisms and need to divide ourselves)
Tissue repair
Regeneration
T/F Certain cells in the body can regenerate while some can’t, just depends on the type
T
Cell turnover rate depends on which ____ we are talking about
tissue
T/F Many tissues see high cell turnover while others never divide
T
Highest turnover rate: ______
blood cells
Lowest turnover rates
Lowest: in neurons, oocytes (female gametes are only a certain number of eggs) and lens cells never replicate
_____ get released every month after puberty
Oocytes
Are arrested in ______ (already started meiosis)
prophase 1
Finish ____ in the fallopian tube, if fertilizes becomes a zygote
meiosis
Sperm on the other hand replicates how much?
unlimited
The plasma membrane has _____ on it that would allow things to be transported in and out or be diffused through phospholipids through active/passive
proteins
Why is cell division so important?
Higher surface area
As a cell grows, _____ increases faster than the surface area
volume
(_______ that brings nutrients in and excrtees waste out - essentially helps cell function and grow)
plasma membrane
That is when a cell has to divide to go back to higher ______ to _____ ratio
SA to volume
Cell grows till reach a point where SA cannot keep up with the demands of ____
volume
Something is wrong if the cell is dividing _____
uncontrollably
SA/V = ____ to function well
high
As a cell grows larger, its SA/V ratio _____
decreases
______ regulate progression through the cell cycle
Checkpoints
If the cell replicated without any control/regulation, it would lead to _____ like cancer grow
tumors
It gets to the point where it can no longer survive so it _____
divides
_____: divide rapidly
proliferate
_____:
Protein
Acts as a transcription factor
Regulates the cell cycle
Guardian of the genome
Cancer cells target
Most tumors have ____ mutated
p53
For example cancer targets _____
Ex: P53
This means that the protein and RNA that have been involved in maintaining the cycle have been ______: rapid proliferation means (overcoming the cell cycle)
deregulated
If cannot fix the mutation the cell will either ______ or ______
arrest cycle or apoptosis
In G1S, ____ come and make sure no mutation in the DNA
Proteins
Cancer targets those proteins that stop the ________
cycle from happening
The first checkpoint is ____
G1S
program cell death is called:
apoptosis (quite common)
_____ drives/is a key regulator of apoptosis
P53
The second checkpoint is ____
G2M
_____: Makes sure the SA/V ratio is large enough so can split into two and survive and looks for missed muations
G2M checkpoint
Cell ensures has all nutrients required to go through the __ phase
M
The third checkpoint is the _______
mitotic spindle checkpoint
Chromosomes line up and spindle pull sister chromatids apart, and for this to occur properly, ____ sister chromatids have to go in one cell and the other three have to go in another (even distribution)
3
happens during:
During metaphase
If cell has more or fewer chromosomes than normal it is called _____ (an example is trisomy 21 or Down syndrome)
aneuploidy
___ is a type of enzyme specifically an enzyme that phosphorates proteins
CDK
But if there is a problem with the attachment of the spindle to the chromosome then both sister chromatids go ______
into one cell
Once activated: it ______ CDK (has a phosphate group attached to it)
phosphorylates
_____ Regulation: Cyclins and CDKs (SAY GO AHEAD PROCEED)
Positive
When they are stuck together, the ______-donating part of the protein becomes activated
phosphate
KEY DRIVER is:
cyclin CDK-activated complex
Both can transcribed and translated into proteins and come together in a _____
complex
This activates the entire complex so now can take the phosphate group and phosphate the ____ protein
target
________ regulation: p53, p21, and Rb (SAY STOP)
Negative
______ regulation means they will stop the cell cycle from proceeding
Negative
Put up a ____ to stop going to cell cycle if something is wrong (not time or mutation sensed)
barrier
The target protein will then go and drive the ______
cell cycle
Now cyclin CDK can’t ______ proteins involved in cell cycling
phosphorylate
Start with a damaged cell, The _____ is a region of the gene that controls the expression of the gene next to it (in this case p21)
promoter
Called a _____ suppressor because they supes possibility of a tumor (if they didn’t stop, the cell cycle would continue and likely develop a tumor)
tumor
The damaged cell is now _____ or _____
arrested or apoptosis
P53 inhibits cyclin-CDK by targeting ____ production
p21 production
Tells ___ gene to make p21 mRNA and then protein
p21
The protein binds to the active ________ (the one that says go) and tells it to stop going by binding to it and inactivating the complex
cyclin CDK complex
The stages and main characteristics of mitosis
Prophase, metaphase, anaphase, telophase. Characterized by chromosome alignment and separation.
____ is a transcription factor, it goes and binds to the promoter and turns it on
p53
The phases and main characteristics of the cell cycle for prokaryotic cells
Binary fission: DNA replication, chromosome segregation, cytokinesis.
The phases and main characteristics of the cell cycle for eukaryotic cells
Interphase (G1, S, G2) and M phase (mitosis, cytokinesis).
The location of DNA in eukaryotic and prokaryotic cells
Eukaryotes: Nucleus.
Prokaryotes: Cytoplasm (nucleoid region).
Why would you NOT target p21?
because it relies on p53
P53 can also trigger _____ if damaged DNA cannot be repaired
apoptosis
The reason why the G1 and G2 phases exist
G1: Cell growth, prep for DNA replication.
G2: Prep for mitosis.
The basic mechanism of DNA recombination in prophase of meiosis
Occurs in prophase I of meiosis via crossing over between homologous chromosomes.
The stage of cell division if given a micrograph or diagram of a dividing cell
Identify based on chromosome behavior (e.g., metaphase = chromosomes aligned in center).
The stages and main characteristics of meiosis
Meiosis I and II. Involves homologous chromosome separation (I) and sister chromatid separation (II).
Purpose of cell division and risk if cells grow too large in size
Growth, repair. Large cells have trouble with nutrient/waste exchange.
The relationship between the distance separating genes and the likelihood of recombination occurring between them
Closer genes recombine less often, while distant genes recombine more frequently.
The distinct stages of the cell cycle
G1, S, G2, M phase.
The randomness of alignment of homologous pairs in metaphase I
Homologous pairs align randomly, increasing genetic diversity.
Location of actively cycling cells in multicellular animals
In tissues like skin, gut lining, bone marrow.
Main characteristics of each stage in the cell cycle
G1: Growth.
S: DNA replication.
G2: Prep for division.
M: Mitosis.
Main role of cell cycle checkpoints
Ensure proper division and DNA integrity.
Examples of situations in which cells would be programmed to die by apoptosis
Damaged DNA, infection, developmental processes.
What is the risk of any protein involved at the cell cycle checkpoints not functioning properly (be specific)?
Uncontrolled division, leading to cancer.
The difference between positive and negative regulation at cell cycle checkpoints
Positive: Promotes cycle progression.
Negative: Stops cycle if issues arise.
What the process of mitosis ensures in subsequent generations
Equal DNA distribution to daughter cells.
Why p53 is considered the guardian of the genome
Prevents damaged cells from dividing, triggers repair/apoptosis.
The stages of mitosis
Prophase, metaphase, anaphase, telophase.
We all look different because of the events that took place during ____and after
meiosis
Events that lead to genetic variation:
-Homologous recombination/crossover
-Independent assortment
-Random fertilization
Homologous recombination/crossover (during _______ and ___ of meiosis)
prophase 1 and 2
Independent assortment (during ____ 1 and 2 of meiosis)
metaphase
_______ (when you have a mature egg and sperm fertilization is random, actual gamete and sperm are random)
Random fertilization
Mitosis: The end product is ______
2 cells called two daughter cells
The two daughter cells in mitosis are ______
genetically identical
Mitosis is a ___-division event
one
The ploidy in mitosis
remains the same
We are ____ (2N individuals)
diploid
Ploidy
(how many sets of unique chromosomes are in that species)
N is the number of unique _______
chromosomes
We have ___ unique chromosomes, but we have 2 sets of them
23
Meiosis is a ___-division event
two
The end product of meiosis is __ cells
4
No _____ during embryogenesis
meiosis
The 4 cells in meiosis end product are all _______
genetically different
The ploidy in meiosis _____
changes
The ploidy goes from ___ to ___, they are
2N to N (now haploid)
The 4 cells have to be haloid because _______
the other set will come from the gamete fertilization
The result is egg (n) and sperm (n) through the process of ____ 1 and 2 come together to form a zygote (2N)
meiosis
Key differences between meiosis 1 and mitosis: ______ during prophase 1 and 2, none in mitosis
Crossover
The ____ will divide and divide to produce an entire organism (mitosis)
zygote
Meiosis only occurs in________ organs after puberty
reproductive organs after puberty
Meiosis 1 produces ____ cells and 2 continues that phase (goes from n-n)
haploid
T/F Meiosis 1 is identical to mitosis
F: not
In meiosis 1 you go from___ to ___ mitosis goes form 2N to 2N (remains same)
2N to N
Meiosis __ is most similar to mitosis
2
_______ chromosomes separate in meiosis 1 (none in mitosis - only sister chromatids separate, but in meiosis 2 sister chromatids do separately)
Homologous
If homologous recombination occurs between 2 identical sister chromatids then there would be ___ genetic diversity
NO
Chromosome is defined by the number of ________
centromeres
When you have a cell with a nucleus that has DNA meshed up, it is called _____
chromatin
Meiosis 1 is ______
reductional
T/F Centromere does not have to be centered all the time
TRUE
If you have a homologous pair, _______ chromatids will cross over
non-sister
Homeolgous pairs are separated in _____ (sister chromatids are not separating)
Anaphase 1
Each strand is ____ chromtaids
sister
Metaphase 1 lining is an _______ ______ because they are aligned in a way independent of each other
independent assortment
Decrease in ploidy in telophase 1 because now you have ___ set of chromosomes
one
The crossover is called:
chiasma (plural: chiasmata)
In meiosis u go from __ to __ ploidy
n to n
T/F In one homologous pair, you cannot have multiple chiasmata
FALSE you can
Recombination creates new combinations of _____
alleles
The difference is the _______
copy number
Alleles A and B will ___ influence each other (very random)
not
The further apart the genes are on a chromosome, the more likely the _____ will occur between them, which means they are separated and not linked
chiasma
Meisos 2 is ________
equational
Each ____ will get a copy of one chromosome
gamete
All ____ chromatids can crossover (they may not all)
four
______ are genes that are more likely to be inherited together (not always or never)
Linked genes
The closer the genes are to each other, the more likely they are:
linked/will be inherited together
All gametes will get different versions of these alleles (the ____ is the same, version of the gene is different)
gene
More is ____ less is ____
n+1, n-1
Random fertilization:
_____ brings DNA from two different parents into the same cell
Zygotes
______ of gametes are different based on how they line up
Genotypes
Independent assortment is predictable or unpredictable
unpredictable
Some chromosomal mutations can lead to abnormal numbers or chromosomes present in gametes after meiosis, this is called:
Aneuploidy
It happens through an event called:
non-disjunction
________ (trisomy 21) has the best outcome
Down syndrome
The ____ you are the more likely for women to have kids with Down syndrome (because spindles become abnormal, more mutations, and chromosomes don’t line up)
older
Trisomy 13:
Patau syndrome
___ (turner syndrome)
X
Trisomy 18:
Edwards syndrome
______: a picture taken by scientists, during METAPHASE, lined up from largest to smallest (has twice the amount of DNA)
Karyotype
___ (not viable)
Y
Some abnormal combinations of sex chromosomes in fertilized zygotes result from ______ of X chromosomes during meiosis in females
nondisjunction
_____ (triple x syndrome)
XXX
Animal life cycle:
Gametes arise by _____
The zygote divides by _____
meiosis
mitosis
___ (Klinefelter syndrome)
XXY
Super male: ___
YY
The reason why meiosis I is “reductional” and meiosis II is “equational”
Reduces chromosome number by half.
Meiosis II (equational): Chromosome number stays the same.
Plant and most fungi life cycle
Gametes arise by _____
Spores are formed by ____
mitosis
meiosis
Characteristics of homologous chromosomes
Same genes, possibly different alleles, one from each parent.
Main differences between mitosis and meiosis
Mitosis: 2 identical diploid cells.
Meiosis: 4 genetically diverse haploid cells.
Some fungi and algae life cycle
Gametes arise by _____
The zygote is divided by ____
mitosis
meiosis
Stage of mitosis or meiosis based on a micrograph or diagram of a dividing cell
Based on chromosome behavior (e.g., homologous pairs in meiosis I).
The relationship between distance between alleles and the likelihood that they will be inherited together; linked genes
Closer alleles = more likely inherited together (linked); distant alleles recombine more often.
Mechanism of recombination during prophase. How do homologues pair in order for all non-sister chromatids to participate in recombination?
Homologues pair, crossing over occurs at chiasmata between non-sister chromatids.
Other mechanisms giving rise to variation in meiosis
Independent assortment, recombination, random fertilization.
Mechanism by which recombination creates novel combinations of alleles
Recombination shuffles alleles, creating new genetic combinations.
Which of the following is mitosis NOT used for?
A. Repair of a wound
B. Regeneration of hair follicles
C.Production of oocyte
D. Development of baby in mother’s womb
C.Production of oocyte (Oocytes are produced via meiosis. The rest are due to mitotic divisions of somatic cells.)
Relationship between age of an oocyte and the risk of offspring having Down Syndrome
Older oocytes have a higher risk of nondisjunction, increasing the chance of trisomy 21.
Mechanisms giving rise to aneuploid products of meiosis
Nondisjunction during meiosis, leading to extra or missing chromosomes.
Life cycles of different organisms. What are the products of mitosis and meiosis in animals, plants, fungi and algae?
Animals: Mitosis = growth; meiosis = gametes.
Plants: Mitosis = growth/gametophyte; meiosis = spores.
Fungi/algae: Mitosis = growth/haploid cells; meiosis = spores
The activity of cyclin-dependent kinases, or CDKs, is controlled by a number of signals. Which of the following signals will most likely lead to activation of p21?
A. Growth factors
B. DNA damage (p21 will be activated if cell
cycle needs to be arrested.
Only option B requires this)
C. Mutation of p53
D. Phosphorylation of CDKs
B. DNA damage (p21 will be activated if cell
cycle needs to be arrested.
What is the harm of a cell continuing to grow in size instead of dividing?
A) The cell will take up too much space and crowd surrounding cells.
B)Nutrients will not be able to enter the cell membrane fast enough to sustain the demands of the cell volume.
C) The smaller surface area will make it easier for toxic substances to leave the plasma membrane.
D) The surface area to volume will increase and prevent the movement of proteins throughout the cell.
B)Nutrients will not be able to enter the cell membrane fast enough to sustain the demands of the cell volume.
