Chapter 12-14 Biology Flashcards
What are the three parts of the Cell Theory?
- Cells are the basic unit of life
- Cells come from pre-existing cells
- All living organisms are composed of 1+ cells
What steps are required for cellular replication
- Replicate DNA (2 copies)
- Separate cytoplasm, DNA, organelles
- Grow cell size
Define chromosome
Bundles of DNA wrapped around histones
Define sister chromatid
Chromatid copies attached at the centromere, both sister chromatids have the same DNA
Define gene
Region that codes for RNA
Chromatids are one strand of ___-stranded DNA
double
Two ___ chromatids make up one chromosome.
sister
Before mitosis, where is cohesion between sister chromatids?
All the way up. After mitosis, cohesion is at the centromere.
I consist of a single, long DNA double helix wrapped around histones, what am I?
Unreplicated chromosome
I consist of two copies of the same DNA helix, what am I?
Replicated chromosome
I consist of condensed DNA wrapped around its histones and I am 10,000x shorter than my original length. What am I?
Condensed replicated chromosome
Why do chromosomes condense?
In order to divide
Why would you see an unraveled chromosome?
So it can be read, replicated, and proteins can be made
Which of the following is the correct order for the phases of the cell cycle?
a) G1, G2, S, and M
b) S, G2, M, and G1
c) S, G1, M, and G2
d) S, G2, G1, and M
B
Which 3 phases of the cell cycle make up interphase?
G1, S, G2
What happens in G1 phase?
-Cell grows larger
-Organelles are copied
-Production of NEW proteins
What happens in S-phase?
S for synthesis
-DNA is synthesized/replicated
What happens in G2 phase?
-Cell grows more
-Duplication of organelles
-Cell begins to reorganize its contents in preparation for mitosis
Interphase v.s. Mitosis
Interphase: cell is not dividing, it’s growing and PREPARING to divide
Mitosis: cell is dividing
A certain species of animal has six pairs of chromosomes. How many sister chromatids do the nuclei of these animals have during G2 phase?
a) 48
b) 12
c) 6
d) 24
D
When does G2 end?
When mitosis begins
What is the difference between a chromosome and a chromatid?
A chromatid is one half of a replicated chromosome, whereas a chromosome consists of DNA wrapped around proteins in a highly organized manner.
What are the 3 types of cell reproductions
- Binary fission (bacteria)
- Meiosis (gametes)
- Mitosis (somatic cells)
Mitosis starts when ___ or body cells divide. When mitosis is completed ___ identical cells are produced
somatic, two
5 stages of Mitosis
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
What is interphase?
-period between two consecutive mitoses
-uncoiled chromosomes
-cells growing/prepared to divide
MOST TIME SPENT FOR CELLS
Centromere v.s. Centrosome
Centromere: connects sister chromatids
Centrosome: where microtubules are made to move chromosomes
What happens in prophase?
-chromosomes condense
-spindle apparatus forms
Mitotic spindle fibers are composed of what cellular components?
a) kinetochores
b) microtubules
c) centrosomes
d) actin
B
What happens in prometaphase?
-nuclear envelope breaks down
-microtubules contact chromosomes at kinetochores
What happens in metaphase?
M for middle
-chromosomes line up in the middle
What happens in anaphase?
A for “Anna being separated from Elsa”
-sister chromatids separate
What is the metaphase plate?
The imaginary plane between two spindle poles
In metaphase each chromosome is held by ____ microtubules from ___ poles.
kinetochore, opposite
After which stage of mitosis are two identical sets of chromosomes created?
Anaphase
Which two forces pull chromosomes apart?
-kinetochore microtubules shrink
-motor proteins of polar microtubules push two poles of cell away from each other
When microtubules move chromosomes during anaphase, ___ subunits are lost from their (+) ends
tubulin
What happens in telophase?
-nuclear envelope begins to forms
-chromosomes begin to decondense
When mitosis is complete, two independent ___ have formed.
nuclei
Cytokinesis in animal cells is when ___-___ interactions pull the plasma membrane inward to divide the cell into two.
actin-myosin
After S phase, what makes up a single chromosome?
a) A single double-stranded DNA molecule
b) Two single-stranded DNA molecules
c) Two daughter chromosomes
d) Two sister chromatids
D
s=synthesis, DNA will have been replicated and sister chromatids will be conjoined
The structures on sister chromatids where microtubules attach.
Kinetochores
The material that makes up eukaryotic chromosomes and consists of DNA molecules with histones.
Chromatin
In what ways does fission differ from mitosis?
-no nucleus
-no packing of DNA
How is fission similar to mitosis?
-copying of DNA
-pinching as seen in cytokinesis
-two poles –> two daughter cells
True or false: Cell-cycle length varies
True
What is the function of the M-phase promoting factor (MPH)?
Tells the cell that it can divide
Present in different concentration throughout the cell cycle
Cyclin (think cycling, goes up and down)
Kinase that transfers phosphate group from ATP to target protein
Cyclin-dependent kinase (CDK)
CDK + Cyclin make up ___
MPF
When does cyclin peak? When does it start to decrease?
M-phase is when cyclin peaks, and decreases when the cell needs to stop cell division and come to a conclusion.
!!! you have to know that cyclin INCREASES in G1 and S phase
With the use of cyclin, the cell cycle is turned on in late ___ and turns off after ___.
G2, anaphase
3 Cell-cycle checkpoints
- G1 checkpoint
- G2 checkpoint
- M checkpoint x2
Why do we have checkpoints in the cell-cycle?
-Make sure the cell is ready for the next phase
-No damaged DNA
What does the G1 checkpoint look for?
-Cell size is sufficient
-Nutrients are sufficient
-Social signals are present
-DNA is undamaged
What does the G2 checkpoint look for?
-If chromosomes have successfully replicated
-DNA is undamaged
-Activated MPF is present
What does the M-phase checkpoint look for? (part one)
-Chromosomes have attached to spindle apparatus
-Chromosomes have properly segregated and MPF is absent
What happens if a checkpoint fails?
-Cell can wait for prereqs to be fulfilled
-If DNA is damaged, P53 will pause cell cycle
-if damage is NOT repaired, apoptosis will occur (cell death)
WHAT PROTEIN IS IMPORTANT FOR PAUSING CELL CYCLE (!!!)
p53