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Biology HL 11 > Cell Division > Flashcards

Cell Division Flashcards

Unit 1, Cell Biology

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1
Q

Importance of cell production

A

New cells need to be produced for growth, maintenance and reproduction

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2
Q

What is zygote

A

Zygote is the original mother cell in a human that through division leads to the trillion of other cells in a human

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3
Q

Define Mitosis

A

Nuclear cell division that produces identical cells.
Daughter cells have the same amount of chromosomes and genes as their mother

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4
Q

Define Meiosis

A

Nuclear cell division that produces genetically unique cells.
Daughter cells have half amount of chromosomes than their mother. Genetic diversity allowing evolution.

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5
Q

What is the first step of eukaryotes cell division

A

They must first divide their nucleus to avoid creating new cells that are lacking a nucleus

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6
Q

Define cell proliferation

A

It is a rapid increase in the number of cells (cell division is faster than cell death)

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7
Q

Importance of cell proliferation

A

in multicellular organisms it is needed for growth, cell replacement and tissue repair

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8
Q

Example of growth

A

In animals, proliferation occurs at a high rate during embryonic phases of growth and continues in juvenile phases
In plants, it is confined to growth regions called meristems

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9
Q

Cell replacement example

A

Skin epidermis cells are replaced throughout a humans life, continuous division below the skin’s surface gradually pushes older cells to the surface.

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10
Q

Example of tissue repair

A

It occrs in undifferentiated stem cells are present such as in the skin, repair can happen in a matter of days

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11
Q

Define cell cycle

A

It is the series of events that occur during the life of a cell. Cells proliferate in the mitosis phase of the cell cycle.

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12
Q

Different phases of mitosis

A

Prophase, metaphase, anaphase and telophase

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13
Q

What is mitotic phase

A

Process of mitosis (nuclear division) followed by cytokinesis (divides the cytoplasm and its contents)

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14
Q

What is Interphase

A

Time between one mitosis and the next
Interphase = G1+S+G2

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15
Q

What is a G1 phase?

A

Phase afer mitosis and before DNA replication, active growth, each chromosome is a single DNA molecule (unduplicated)

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16
Q

What is a S phase?

A

All DNA in the nucleus is replicated or copied resulting in identical pairs of DNA

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17
Q

What is a G2 phase?

A

More growth and preparation for division, DNA still duplicated

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18
Q

What happens to chromosomes after S phase

A

After S phase, there will be pairs of idential molecules (chromosomes) due to the repliction of DNA

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19
Q

What is a cohesin?

A

Cohesin complex holds the chromatids together until anaphase of mitosis

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20
Q

What is centromere?

A

A constricted region of a chromosome where cohesin loops join the chromatids

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21
Q

What happens to chromosomes during mitosis

A

Chromosomes are in a condensed and organized form

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22
Q

What is chromosomes made up of?

A

Chromosomes are made up of DNA wrapped around proteins called histones

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23
Q

Define Cyclins

A

They are a group of proteins that help progress the cell through the cell cycle

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24
Q

Function of each cyclins

A

Cyclin activates a different group of proteins, and the group of proteins is specific to the desired actions of that point in the cell cycle.

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25
Q

Metaphase Checkpoint?

A

Chromosome spindle attachment

26
Q

G1 Checkpoint?

A
  • Nutrients
  • Growth factors
  • DNA damage
27
Q

G2 Checkpoint?

A
  • Cell size
  • DNA replication
28
Q

What do chromosomes need ot be condensed?

A

During mitosis they need to be moved and condensing them prevents them from getting tangled or broken

29
Q

Processs of condensing of the DNA?

A

Condensing begins by DNA wrapping around histone proteins forming nucleosomes and linking them together

30
Q

Define Kinetechore

A

They attach chromosomes to the spindle in order to move the chromosomes during mitosis

31
Q

What are chromosomes moved by?

A

Chromosomes are moved by microtubles (made of protein tubulin) that assemble and reassemble quickly

32
Q

What happens to DNA during interphase?

A

DNA during interphase is decondensed and dispersed in the nucleus in a form called chromatin, which directs many cell activities.

33
Q

What happens during interphase?

A

Volume of cytoplasm increases so many organelles must be chemically produced
Metabolic reactions are occuring
Many proteins and molecules needed for growth are being made

34
Q

Define heterochromatin

A

DNA that lacks genes necessary for cell activities, during interphase it remains condensed

35
Q

What are different phases of mitosis?

A

Prophase, Metaphase, Anaphase and Telophase

36
Q

What happens during prophase

A

It is the beginning of the phase, chromosomes condense (becomes visible in microscopes)

37
Q
A
38
Q

What happens during metaphase?

A

Chromosomes align at the center (equator or metaphase plate)

39
Q

What happens during anaphase?

A

Duplicated chromosomes are split, chromatids pulled to each pole

40
Q

What happens during Telophase?

A

Chromosomes reach poles, decondense and spread out

41
Q

Fomula to find Mitotic index

A

Mitotic index= number of cells dividing/Total number of cells

42
Q

Define cytokinesis

A

Cytokinesis is a division of the cytoplasm and all its contents (organelles etc.) between the two daughter cells.

43
Q

Quick Note

A

Mitosis + Cytokinesis = Cell Division

44
Q

Is it okay for cytokinesis division to be unequal?

A

Some organelles can only be produced from pre-existing organelles and the daughter cells will survive if they have at least a nucleus and one of such organelles

45
Q

What happens to animal cells during cytokinesis?

A

A ring of contractile protein immediately inside the plasma membrane at the equator pulls the plasma membrane inward.
The inward pull on the plasma membrane produces the characterstic cleavage furrow (The seperating line)
When the cleavage furrow reaches the centre of the cells it is pinched apart to form two daughter cells.

46
Q

What happens to plant cells during cytokinesis

A

During telophase, membrane-enclosed vesicles derived from the Golgi apparatus migrate to the centre of the cell.
The tubular structures merge to form two layers of plasma membrane, cell plate
The cell plate continues to develop until it connects with the existing cell’s plasma membrane.
Two daughter cells are formed
Vesicles deposit, by exocytosis, pectins and other substances in the lumen between the daughter cells to form the middle lamella
Both daughter cell secrete cellulose to form their new adjoining cell walls.

47
Q

Example of unequal cytokinesis?

A

Yeast, they reproduce asexually, called budding and an outgrowth of the mother cell receives a nuclei but only small amounts of cytoplasm. A wall forms separating them, small outgrowth splits them.

48
Q

Define Mutagen

A

A substance that increases the chances of tumor formation

49
Q

Effects of Mutation

A

Mutation to genes in a cell can cause the loss of control over cell division (can be passed on)
It can result in cells increasing exponentially forming tumors

50
Q

Two main types of mutagens?

A
  1. Chemicals, labelled as carcinogenic
  2. High energy radiation (xrays, uv rays)
51
Q

What are two main groups of genes that can change a normal cell into a tumor?

A
  1. Proto-oncogene
  2. Tumor suppressor genes
52
Q

What are proto-oncogene genes?

A

They are genes that regulate expression (turning genes on/off) of genes involved with cell proliferation, pathways involved in cell cycle control, or growth factors.

53
Q

How can proto-oncogene cause cancer?

A

Proto-oncogenes can mutate into a oncogenes, meaning the mutations (cahnges to the gene) make it activate when it is not supposed to, causing cancer

54
Q

What is tumor suppressor genes?

A

They are genes that prevent cell proliferation (putting a break at the cell cycle checkpoints), correct errors in DNA replication, have roles in apoposis (programmed cell deaths)

55
Q

How can mutations to tumor suppressor genes cause cancer?

A

It can make the tumor suppressor genes not function properly and increase risk of tumor formation. Often many mutations are required before forming of tumors.

56
Q

Define primary tumor

A

The cells that divide to form a tumor at the original location it was formed (the cells often stick to each other forming a single mass)

57
Q

Characteristics of primary tumor

A

They are unlikely to cause harm
Not yet considered cancerous

58
Q

Define secondary tumor

A

When cells detach from a primary tumor and invade neighboring tissue or move to other tissue locations throught he blood/lymph

59
Q

Characteristics of secondary tumor

A

The cells will continue to divide and form more tumor

60
Q

Define malignant tumor

A

Tumors that spread to form secondary tumors

61
Q

Define apoptosis

A

Self distrupting of damaged cells to ensure that irreparable cells will not divide

Biology HL 11 (13 decks)

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