The cell cycle, growth, death and differentiation

Question 1

Apoptosis

Answer 1

Programmed cell death

1. Activation of caspases (signalling moleules)
2. Seperation from adjacent cells
3. Collapse of cytoskeleton
4. Cell shrinkage
5. Blebbing of the PM
6. Cell breaking apart into apoptic bodies

Question 2

Necrosis

Answer 2

Accidental cell death
Affects large and compact clusters of cells
Messy explosion
Cell contents released in uncontrolled manner
Caused by:
* Physical damage
* Lack of oxygen
* Toxins
* Pathogens

Question 3

Why do cells die

Answer 3

• Regulate no. of cells in body
• Remove damaged cells
• Faults during mitosis
• Unwanted

Question 4

Mitosis

Answer 4

Cell replication in eukaryotic cells
PMAT

Question 5

Interphase

Answer 5

before mitosis
G1, S, G2
cell grows, performs normal functions and replicates DNA

Question 6

G1 (interphase)

Answer 6

Cell grows and performs normal functions

Question 7

G1 checkpoint

Answer 7

End of G1 phase before DNA synthesis.
AKA restiction point.
Checks if there are enough resources for cell division, if the cell is large enough, and checks DNA condition

Question 8

S phase (interphase)

Answer 8

DNA is duplicated and synthesised in preperation for mitosis

Question 9

G2 (interphase)

Answer 9

Cell continues to grow.
Cell contents are reorganised in preperation for mitosis

Question 10

G2 checkpoint

Answer 10

This checkpoint performs the same checks at the G1 checkpoint however:
Checks the DNA to ensure it has been replicated correctly with no damage

Question 11

Prophase

Answer 11

Double stranded chromosomes become visible and plump
Spindle fibres form

Question 12

Where are the checkpoints

Answer 12

Metaphase, end of G1, G2

Question 13

Metaphase

Answer 13

Chromosome line up at the equator of the cell.
Spindle fibres line up

Question 14

Anaphase

Answer 14

Chromosomes are pulled apart by the centromere and cell spindles move to the opposite ends of the cell

Question 14

Anaphase

Answer 14

Chromosomes are pulled apart by the centromere and cell spindles move to the opposite ends of the cell

Question 15

Telophase

Answer 15

Two nuclei form, each with the diploid number of chromosomes

Question 16

Cytokenesis

Answer 16

The seperation of the new nuclei

Question 17

Cytokenesis in animal cells

Answer 17

Ring of actin filaments form around the equator of the cell.
Tightens to form cleavage furrow.
Cell splits

Question 18

Cytokenesis in plant cells

Answer 18

Vesicles move to the equator.
Line up and fuse to form 2 membranes call the cell plate.
A new cell wall is laid down between the membranes which fuses with the existing cell wall

Question 19

G0 phase

Answer 19

AKA the resting phase.
If the conditions are not right for cell division the cell will enter this phase.
Temporary stage, but some specialised cells remain in the G0 stage permenantly.
The cell will remain here until signalled to restart cell replication

Question 20

DNA replication

Answer 20

Complementary base pairing (A-T, C-G)
DNA unzipped by special enzymes to form 2 single strands.

Question 21

Binary fission

Answer 21

Replication in prokaryotes
Reproduction
Cloning
Quick
Simple

Question 22

Binary fission vs Mitosis

Answer 22

Mitosis:
* Eukaryotes
* more complex
* Used for growth
Binary fission:
* Prokaryotes
* Simple
* Used for reproduction

Question 23

External cell cycle regulations

Answer 23

Contact inhibition:
* crowding from neighhbouring cells
* Causes slower cell cycle
Tumor:
* Release factors that stimulation division of nearby capillary cells to increase nearby blood supply.
Environmental factors:
* Temp, pH, nutrients, etc.
Mitogens:
* Special molecules taht promote cell division.

Question 24

Cell repair

Answer 24

Special enzymes detect and repair DNA damage. Enzymes run along the DNA to check correct replication These repairs can only work for minor damage.

Question 25

Types of tumors

Answer 25

benign: localised, doesn't dev. into cancer Potentially malignant: localised, may invade other tissue and dev. into cancer. Malignant: Masses that invade other tissue and dev. into cancer.

Question 26

Cancer

Answer 26

Uncrontrolled cell growth and replication. Ignore checkpoints Look odd Release factors that increase nearby blood supply. Can mutate can replicate an unlimited amount of times

Question 27

Factors of uncontrolled cell division

Answer 27

Genetic factor: Mutations in enzymes that regulate cell division and death can increase risk of cancer. Proto-oncogens: Stimulate cell division. Mutations can change them into oncogens that cause uncontrolled cell division. Tumour suppressor genes: Mutations in these genes that code fir proteins that regulate cell division and death can increase risk of cancer. Inherited genes:Predisposition to a higher risk of cancer due to inherited genes.

Question 28

Stem cells

Answer 28

Undifferentiated cells. Retain the ability to develop into different cell types. Functions include body growth and development, and tissue repair. Capable of self renewal: Can replicate to form more stem cells.

Question 29

Adult stem cells

Answer 29

In small numbers in tissues such as bone marrow,mspinal cord and germ cells. Do not replicate indefinitely Naturally repair and regenrate old/damaged tissue. Differentiate ino a limited range of cells. Multi/unipotent

Question 30

Embryonic stem cells

Answer 30

Come from embryos, more specifically the zygote and blastocyst stage. Obtained from surplus IVF programs. Replicate indefinitely. Totipotent or pluripotent.

Question 31

cell differentiation

Answer 31

The process in which a stem cell changes to have a specialised function.

Question 32

Totipotent

Answer 32

Can differentiate into embryonic and extra-embyronic cells such as another embryo. Found within 3 days of fertilization.

Question 33

Pluripotent

Answer 33

Differentiate into the 3 germ layers: ectoderm, mesoderm and endoderm. Found in blastocyst (5-6 days)

Question 34

Multipotent

Answer 34

Can differentiate into cells in the same germ layer.

Question 35

Unipotent

Answer 35

Can only differentiate into 1 type of cell.

Question 36

Why do cells replicate

Answer 36

For growth and to replace damaged/dead cells