Inheritance of DNA 2D part 2 (textbook) Mitosis+cell cycle regulation

Question 1

All cells in all organisms that have ever lived are

Answer 1

descended from previous cells in an unbroken chan of cell division stretching billions of years into the past

Question 2

Cell cycle in prokaryotic organisms (3)

Answer 2

B period: birth to inititation of DNA replication the cell grows in size,

C period: The chromosome is replicated and the resulting daughter chromosomes moev to opposute ends during the C period

D period: The cell divides by binary fission as plasma membrane grows inward and a new cell wall is formed.

Question 3

binary fission (6)

What it is+steps

Answer 3

mechanism of prokaryotic cell division

replication begins at orgin of replication

Bacterial chromosome (template and daugter) is attached to the inner membrane

Cell enlongates at the ends and bacterial chromosomes separate

inward growth of plasma membrane and partition assembly of new cell wall diving replicated DNA

Produce 2 daughter cells

Question 4

The ori region of the chromosomes is (2)

Answer 4

in the middle of the cell where the enzymes for DNA replication are located

Question 5

prokaryotic mechanism of cell division vs eukaryotic mechanism of cell division effieciency

Answer 5

The prokaryotic mechanism of cell dividion works effectively because most prokaryotic organisms have only a single chromosome. The genectic info of eukaryotes are divided among several linear chromosomes so if a eukaryotuc daughter fails to receive a copy of even one of the several chromosomes it is lethal.

Question 6

during most of the cell cycle it eukaryotic chromosomes are contained within the

Answer 6

nuclear membrane

Question 7

diploid (2)

Answer 7

have two copies of each type of chromosomes in their nuclei

2n

Question 8

haploid n

Answer 8

only one copy of each type of chromosome in their nucleus

n

Question 9

ploidy

Answer 9

the number of chromosome sets

For example, haploid means one set and diploid means two sets.

Question 10

before a cell divides in mitosis (what major change does it undergo)

Answer 10

replication if the DNA in a given chromosome produces two nearly indentical copies of that chromosome called sister chromatids

Question 11

newly formed sister chromatids are held together————During mitosis the ——-are ____and _______

Answer 11

along their length by proteins called cohesins. Duirn mitosis the cohesins are removed and the sister chromatids are separted with one of each pair going to each of the daughter nuclei.

Question 12

Interphase
(3)
+what is included in this phase
+time wise
+ genes during this phase

Answer 12

Comprises of g1, g2 and s phase

First and longest stage

an appropriate suite of genes are actively expressed to support cell maintanenance and metabolism. Cells are foing their job during interphase

Question 13

G1 phase (2)

+what happens to cells destined to not divide

Answer 13

the cell carries out its function and in some cases grow

phase where many cells stop dividing. Cells that are not destined to divide immediately enter g0

Question 14

S phase

Answer 14

DNA replication and chromosome duplication occur (chromosomes are not visible)
Centrioles duplicate

Question 15

G2 phase

Answer 15

A brief gap in the cell cycle during which cell growth continues and the cell prepares for mitoisis

Question 16

Which phase in eukaryotic cell cycle varies in length?

what does division rate depend on?

Answer 16

G1 is the only phase that varies in lentgh. Thus whether cells divide rapidly or slowly depends primarily on the length of G1.

Question 17

G0 (2)

Answer 17

resting phase or quiescene, not actively dividing
​
a cell is not actively preparing to divide, it’s just doing its job. For instance, it might conduct signals as a neuron (like the one in the drawing below) or store carbohydrates as a liver cell.

Question 18

During all stages of interphase, the chromosomes are

Answer 18

organized but relatively loosely packaged within the nucleus

Question 19

During mitosis what happens in the nucleus and cytoplasm?

Answer 19

In the nucleus, normal gene expression decreases, DNA condenses and kinetochores are built up.

In the cytoplasm, the cytoskeleton that normally attends to cell shape, motility and the movement of organelles now prepares to ensure accurate chromosome positioning.

Question 20

Prophase (3)

What happens to dna? To stuff inside cell?

Answer 20

chromosomes that were replicated during interphase begin to condense into compact rodlike structures. This is done by winding the double helix twice around a complex of small positively charged proteins to form a nucleosome.

while condensing, the nucleous disapears causing a shutdown of all types of RNA synthesis including the ribosomal rna made in nucleolus. In the cytoplasm, the mitotic spindle begins to form between the two centrosomes as they start migrating towards the opposite ends of the cell to form spindle poles. The spindle developes as bundles of microtubules that radiate from the spindle poles.

Question 21

Prometaphase

marked by..

Answer 21

The nuclear membrane breaks down (exposing chromosomes) marking begining of prometaphase
Bundles of spindle microtubules grow from centrosomes at the opposing spindle poles towards the centre of the cell. Some developing spindle microtubules enter the former nuclear area and attach at the centromere of chromosomes.

By this time kinetochore (complex of several protein) has formed on each chromatid at the centromere

Question 22

How many kinetochore per chromosome

Answer 22

2

Question 23

microtubules binding to kinetochore are important because …

Not abt seperating chromosomes…

Answer 23

These connections determine the outcome of mitosis because they attach the sister chromatids of each chromosomes to microtubules leading to the opposute spindle poles

Question 24

Metaphase

+characteritic shape

Answer 24

During metaphase, the spindle reaches its final form and the chromosomes move to metaphase plate. Chromosomes complete their condensation in this stage and assume their characteristic shape as determined by the location of the centromere and the length and thickness od the chromatid arms

Question 25

The shape of an individual chromosome is visible only when it is

Answer 25

highly condensed

Question 26

karyotype

Answer 26

The complete collection of condensed chromosomes arranged acording to size and shape

Question 27

Anaphase

+first sign of chromosome movement
+kinetochore/tubules

Answer 27

Sister chromatids separate and move to opposite spindle poles. Cohesion degrades. The first sign of chromosome movement are seen at the centromeres as the kinetochores are the first sections to move towatds opposite poles, Movement continues until the seperated chromoosomes (daughter chromosomes) have reaches the two poles.

As kinetochore passes thru the tubles it dissambles the tubules.

Question 28

Telophase

Answer 28

The spindle disassembles and the chromosomes at each spindle pole decondense and return to the extended state typical of interphase. Nucleoulus reappears, RNA transcription resumes and new nuclear envelope forms around the chromosomes at each poles. The cyctoskeleton returns to normal interaphase responsibilities.

Question 29

Centrioles vs centrosome plus what happens in mitosis with them

Answer 29

In S phase, centrioles within centrosomes doubled into pairs ( so 4 centrioles in one centromere).

In prophase as the centrosome start to move it splits you get 2 centrosome.

Question 30

cytokinesis

+what happens after+when it occurs

Answer 30

the division of the cytoplasm
Can begin in telophase or even late anaphase. By the end of cytokinesis, daughter cell is progressed to the interphase stage and entered the G1 phase of the next cell cycle.

Question 31

Cytokinesis in different kindoms of eukaryotic organisms

Answer 31

In animals, protist and many fungi a groove deepend and the cytoplasm is eventually cut into two parts

In plants, theres a new cell wall or plate that forms between the daughter nuclei and grows laterally until it divides the cytoplasm. There are vesicles from gogi that has cellulose and etc and fuse to release content,

Question 32

The plane of cytoplasmic division is determined by

Answer 32

the layer of microtubules that persist at the former spindle midpoint

Question 33

control proteins

+what it do plus ex

Answer 33

cyclin

controls progression through the cell cycle

Question 34

G1/S checkpoint

what it does, what it targets, what need to happen

Answer 34

mechanism governing cell cycle determine whether the cell wil proceed through the rest of the cell cycle and divide.

The cell arrests the at the G1/S checkpoint if the DNA is damaged by radiation or chemicals. This checkpoint is also where cells read extracellular signals for cell growth and division. If hormones/growth factors are needed for stimulating cell growth is absent the cells may arrest at this checkpoint.

If there are damages, it has to be fixed

Question 35

M checkpoint

what does it acess?+why is it essential?

Answer 35

Acess if the chromosomes are attached properly to the mitotic spindle so that they will align correctly at the metaphase plate. This checkpoint is essentation asseperation in anaphase depends on correct alignment in metaphase.

Question 36

Once a cell beings anaphase

Answer 36

there are no more checkpoints and it is irreversibly commited to completing Mitosis.

Question 37

CDK

what it do+concentration

Answer 37

cyclin dependent kinases

CDK is a protein kinase that phosphorolates and regulates the activity of target proteins. They are cyclin dependent because they are active only when bound to a cyclin molecule. Concentration of CDK stays constant. Through phosphorlation, each active CDK regulates particular target proteins that play roles in controling key evets of the cell cycle,

drives cell cycle

Question 38

Cyclin concentration …

Answer 38

cycles through high and low levels as the cell cycle progresses.

Question 39

P53+its 3 jobs

Answer 39

inhibit CDK to stop wheel from turning

If ther eis problem: First, it stops the cell cycle at the G1checkpoint by triggering production of Cdk inhibitor (CKI) proteins. The CKI proteins bind to Cdk-cyclin complexes and block their activity (see diagram below), buying time for DNA repair. p53’s second job is to activate DNA repair enzymes. If DNA damage is not fixable, p53 will play its third and final role: triggering programmed cell death so damaged DNA is not passed on.

Question 40

Metastasis

Answer 40

when cancer cells lose their adhesions to other cells and necome active mobile. They break lose from original tumoir spread throughpit the body and grow into new tumours in other body regions.

Question 41

oncogenes

what can it cause, what do they begin as….

Answer 41

Activated oncogenes can cause those cells designated for apoptosis to survive and proliferate instead. Most oncogenes began as proto-oncogenes: normal genes involved in cell growth and proliferation or inhibition of apoptosis. If, through mutation, normal genes promoting cellular growth are up-regulated (gain-of-function mutation), they will predispose the cell to cancer; thus, they are termed “oncogenes”

Question 42

apoptosis

Answer 42

Programmed cell death

Question 43

caspase

Answer 43

involved in cell death

activate dna degradation and distrupted mitochondria function