The cell cycle, growth, death and differentiation Flashcards

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1
Q

Apoptosis

A

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
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2
Q

Necrosis

A

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

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3
Q

Why do cells die

A
  • Regulate no. of cells in body
  • Remove damaged cells
  • Faults during mitosis
  • Unwanted
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4
Q

Mitosis

A

Cell replication in eukaryotic cells
PMAT

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5
Q

Interphase

A

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

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6
Q

G1 (interphase)

A

Cell grows and performs normal functions

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7
Q

G1 checkpoint

A

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

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8
Q

S phase (interphase)

A

DNA is duplicated and synthesised in preperation for mitosis

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9
Q

G2 (interphase)

A

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

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10
Q

G2 checkpoint

A

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

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11
Q

Prophase

A

Double stranded chromosomes become visible and plump
Spindle fibres form

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12
Q

Where are the checkpoints

A

Metaphase, end of G1, G2

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13
Q

Metaphase

A

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

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14
Q

Anaphase

A

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

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14
Q

Anaphase

A

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

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15
Q

Telophase

A

Two nuclei form, each with the diploid number of chromosomes

16
Q

Cytokenesis

A

The seperation of the new nuclei

17
Q

Cytokenesis in animal cells

A

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

18
Q

Cytokenesis in plant cells

A

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

19
Q

G0 phase

A

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

20
Q

DNA replication

A

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

21
Q

Binary fission

A

Replication in prokaryotes
Reproduction
Cloning
Quick
Simple

22
Q

Binary fission vs Mitosis

A

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

23
Q

External cell cycle regulations

A

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.

24
Q

Cell repair

A

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

25
Q

Types of tumors

A

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.

26
Q

Cancer

A

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

27
Q

Factors of uncontrolled cell division

A

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.

28
Q

Stem cells

A

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.

29
Q

Adult stem cells

A

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

30
Q

Embryonic stem cells

A

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

31
Q

cell differentiation

A

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

32
Q

Totipotent

A

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

33
Q

Pluripotent

A

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

34
Q

Multipotent

A

Can differentiate into cells in the same germ layer.

35
Q

Unipotent

A

Can only differentiate into 1 type of cell.

36
Q

Why do cells replicate

A

For growth and to replace damaged/dead cells