Chapter 12: Flashcards
What are nonproductive cells called?
somatic
What are reproductive cells called?
gamatic cells
How many cells are produced in somatic cell division?
2 identical
How many chromosomes are in somatic cells?
46
How many cells are in gametes?
23
What does DNA contain?
chromosome
Each gene is for one __________
characteristic
What does chromatin contain?
DNA and protein
What is asexual reproduction?
a single individual passes all of its genes to its offspring without the fusion of gametes
What is a clone?
a group of genetically identical individuals from the same parent
What is sexual reproduction?
two parents give rise to offspring that have unique combinations of genes inherited from the two parents
What method do hydra cells use to reproduce?
The budding method
What is a karyotype?
is an ordered display of the pairs of chromosomes from a cell
What is the 22 chromosome?
Autosome
xx =
female
xy =
male
What is a diploid cell?
(n + n) has two sets of chromosomes
What is a haploid cell?
(n) has one set of chromosomes
For humans what is the haploid #?
23
What is the chromosome of an unfertilized egg?
x
What is a zygote?
A fertilized egg that has one set of chromosomes from each parent
What is the division of somatic cells called?
mitosis
What is the division of gamete cells called?
meiosis
Is a zygote a haploid or diploid?
diploid
How many stages are there in meiosis?
2
What is the stage before meiosis?
interphase
What enters meiosis I?
A pair of homologous chromosomes in one cell
What happens in meiosis I?
homologous chromosomes separate into haploid cells with duplicated chromosomes
What happens in meiosis II?
sister chromatids separate
What are the 4 parts of meiosis I?
prophase I
metaphase I
anaphase I
telophase I and cytokinesis
What is metaphase I?
All chromosome pairs are aligned int he center of the cells
In metaphase I, microtubules are attached to what?
kinetochore
What is the end product of meiosis I?
2 cells containing half of the DNA that the original cell started with
Where is the chiasmata?
prophase I
What is a chiasmata?
the cross over point os sister chromosomes from mom and dad
What is a synaptonemal complex?
The zipper like structure that holds two parent chromosomes together
Is there chiasmata in mitosis?
no
Mitosis takes 2n and creates ________
2 more cells of 2n
Meiosis takes 2n and creates ________
4 n cells
What is the narrow part of a chromosomes called?
centromere
CHECK
After duplication in interphase what are chromosomes referred as?
sister chromatid
What is cell cycle?
Life from being a parent cell to two daughter cells
What are the three major steps in mitosis?
- replicates its DNA
- splits two copies to either side of the cell
- entire cells splits in half into two daughter cells
What is a cells genetic information called?
genome
What is the difference between a eukaryotic and prokaryotic genome?
A prokaryotic cell has a genome of one single stand of DNA while a eukaryotic has multiple
What is a chromosome?
tightly packed DNA molecule
What is chromatin?
DNA molecule + associated proteins
When condensed what does chromatin make up?
chromosomes
What is a chromosome called after being duplicated?
Sister chromatid
What connects sister chromatids?
cohesions
What is a centromere?
A region made up of repetitive sequences of DNA where the two sister chromatids are most connected
What causes a duplicated chromosome to have a “narrow waist”?
condensed DNA caused by bound proteins
What is the portion of the chromatid on either side of the centromere referred to as?
the arm of the chromatid
Which process of cell division is used to replace damaged cells?
mitosis
which process of cell division is used to produce gametes?
meiosis
What is typically the shortest part of the cell cycle?
mitotic phase
What accounts for 90% of the cell cycle?
interphase
What are the 3 smaller steps of interphase?
G1, S, and G2
Where does duplication of the chromosomes occur?
S phase
What are the main purposes of the G1 and G2 phase?
to grow the cell
Where does the division of the cell actually happen in somatic cells?
Mitotic Phase
What are the 5 stages of Mitosis?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase/Cytokinesis
What stage do mitotic spindles develop?
Prophase
What are mitotic spindles made of?
microtubules
What are centrosomes?
Regions in animal cells that organize the microtubules of the mitotic spindles?
How many centrosomes are there in G2 of Interphase?
2
Are the chromosomes leaving G2 phase condensed or uncondensed?
uncondensed
In what stage of mitosis does the mitotic spindle form?
Prophase
In what stage of mitosis do the sister chromatids condense and match up via cohesions?
Prophase
What is an Aster?
The radial arrays of shorter microtubules that extend from the centrosome
What happens to the nucleoli in prophase of mitosis?
it disappears
What happens to the centromeres in Prophase of mitosis?
they move away from each other due to microtubules
In what stage of mitosis does the nuclear envelope fragment?
Prometaphase
what does nuclear envelope fragmentation allow in prometaphase?
Allows for microtubules extending from the centrosome to invade the nuclear area
What is a kinetochore?
A specialized protein lovcated on the centromere
What happens when a microtubules attached to a kinetochore?
they are pulled toward the pole that the microtubules extend from
What stops the movement of chromosome towards the pole of the microtubules during prometaphase?
When another microtubule attaches to the other kinetochore of the sister chromatid
What do microtubules do that do not connect to kinetochore?
They connect to opposite microtubules, expanding the cell
In what stage of mitosis are centrosomes on the opposite side of the cells?
Metaphase
What is the main event of metaphase?
Chromosomes line up on metaphase plate
What is metaphase plate/
the equator of the cell
Where do the chromosomes centromeres lie in metaphase of mitosis?
on the metaphase plate
What is the shortest stage of mitosis?
Anaphase
What is the first step of Anaphase in mitosis?
cohesion proteins of sister chromatids are cleaved
What is the main event of Anaphase?
Two sister chromatids are separated into chromosomes and pulled to opposite poles
Elongation during anaphase of mitosis is due to what?
nonkineuechore microtubules lengthening
Why do daughter chromosomes in Anaphase move towards opposite poles?
Their kinetochore microtubles shorten
If one where to start off with 10 chromosomes, how many would be on EACH pole in Anaphase and how many would there be in total?
20 in total
10 on each pole
What is the main event of telophase in mitosis?
Two separate nucleus are formed.
What is the main event of cytokinesis in mitosis?
The cell divides into two cells
What is a cleavage furrow?
In cytokinesis the point at which the cell is pinching in
Regarding the cleavage furrow, what is on the cytoplasmic side?
actin microfilaments
What do actin microfilaments react with that cause the ring to contract?
myosin
Cleavage furrow is to animals cells as _________ is to plant cells?
Cell Plate
What is the cell plate made of?
vesicles
What is binary fission?
When a cell grows twice its size and then divides in half
What type of reproduction is binary fission?
asexual
In bacteria, how is DNA carried
in a circular DNA molecules and associated proteins
What is the origin of replication?
specific place on a bacterial chromosome that begins to replicate
What are the steps of binary fission?
- origin replicates
- origin moves to opposing sides of the cell
- chromosome continues to replicate and cell elongates
- proteins cause plasma membrane to pinch in
- Cell completely divides
What are the sequential events of the cell cycle directed by?
Cell cycle control system
What is a cell checkpoint?
A point of the cell cycle control system that has stop/go signals
Where are the 3 important checkpoints of mitosis founds?
G1, G2, and M phase
What are the two main regulatory proteins of the cell cycle control system?
Cdks and cyclins
What are protein kinases?
Enzymes that activate other proteins via phosphorylation
T or F? most protein kinases are in an inactive form?
T
What must a Cdk attach to activate?
cyclin
Of the proteins involved in the cell cycle control system, which is held at concentration throughout the growth of the cell?
cdk
A cyclin + CDK = ?
MPF
What does MPF stand for?
M-Phase Promoting Factor
Peaks of MPF correspond to peaks in what?
cyclin concentration
When are MPF concentrations at their highest in regard to the different stages of mitosis?
metaphase
What causes MPF to switch off?
cyclin is destroyed
What is arguable the most important checkpoint in mitosis?
The G1 checkpoint
What is the non dividing state of a cell called?
G0 phase
What phase are most cells in our body kept at?
G0 phase
Anaphase not continuing without ALL kinetochore molecules being connected to microtubules is an example of what kind of signal/
internal
What is a growth factor?
A protein released by certain cells that stimulates other cells to divide
During injury PDGF molecules are released by platelets, detected by receptors on the outside of the plasma membrane, and thus trigger cells to divide. PDGF in this case is an example of what?
A growth factor
Growth factors are examples of what kind of signal?
external
What is density-dependent inhibition?
The phenomenon in which crowded cells stop dividing?
Why do cells stop dividing when they are touching?
Both have receptor for a surface cell protein on other cells
What is anchorage dependence?
To divide, cells must be attached to a substratum
What is the overarching difference between cancer calls and regular cells?
Cancer cells have deranged cell cycles
What is the term for when a normal cell begins to behave like a cancer cell?
transformation
Normally, how many times will a cell divide?
20-50
What is a benign tumor?
A stagnant tumor
What is a malignant tumor?
A tumor that is able to spread to other tissue
What is metastasis?
The movement of cancerous cells
How is a localized tumor treated?
High energy radiation
How is cancer treated when it has spread?
chemotherapy
What doe chemotherapy do on a cellular level?
Causes cells to stop dividing because block the creation of mitotic spindle