5.1 The Mitotic Cell Cycle Flashcards Preview

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Flashcards in 5.1 The Mitotic Cell Cycle Deck (33)
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1
Q

Genome

A

the complete set of genes or genetic material (haploid set) present in a cell or organism.

2
Q

Chromatin

A

Combination of DNA and histone proteins that makes up eukaryotic chromosomes (loosely coiled form of chromosomes)

3
Q

Chromatid

A

Two threadlike strands into which a chromosome divides longitudinally during cell division - each contains one molecule double helix of DNA

4
Q

Centromere

A

Narrow region where two chromatids are joined together

5
Q

Heterochromatin

A

Eukaryotic chromatin remains highly compacted (easier to separate) & generally not transcribed - genes mostly inactive

6
Q

Euchromatin

A

Less condensed form of eukaryotic chromatin available for transcription

7
Q

Chromosome

A

A molecule of DNA, associated with histones (protein) carrying genetic information in the form of genes. The DNA is tightly coiled around the histones, so that the long DNA molecule packs into a very small space

8
Q

Telomere

A

Regions of non-coding DNA at end of chromosomes which prevents loss of DNA

9
Q

Diploid nucleus

A

Contains 2 sets of chromosomes; 1 set = 23 chromosomes (2n = 46)

10
Q

Autosomes

A

All chromosomes except sex chromosomes

11
Q

Haploid nucleus

A

Contains 1 set of chromosomes (n = 23)

12
Q

Interphase

A

Phase of the cell cycle in which a typical cell spends most of its life in this phase - cell copies its DNA in preparation for mitosis

13
Q

Interphase stages

A
  • G1: cell makes RNA, enzymes, proteins for growth and at end of G1 the cell becomes committed to dividing or not dividing
  • S: DNA replication - each chromosome replicates to have two identical chromatids
  • G2: cell continues to grow and new DNA checked for any errors repaired before proceeding to mitosis
14
Q

Mitosis (M Phase)

A

Nuclear division in which two cells are genetically identical with diploid nucleus

15
Q

Importance of mitosis

A
  • Asexual reproduction
  • Cell replacement
  • Repairment of damaged tissues
  • Cell growth
16
Q

Early prophase

A

1) Centrioles replicate just before prophase
2) Chromosomes start to appear as the chromatin condenses and coils up, becoming shorter
3) Intact nuclear envelope

17
Q

Late prophase

A

1) Chromosomes are seen to consist of two identical chromatids; each chromatid contains one DNA molecule
2) Centrioles move to opposite ends of nucleus where they form poles of the spindle
3) Nuclear envelope disappears (it breaks up into small vesicles which are not visible with light microscope)
4) Nucleolus disappears (forms part of several chromosomes)

18
Q

Metaphase

A

1) Nuclear envelope disappears
2) Each centriole reaches a pole
3) Spindle (microtubules) is completely formed by centrioles
4) Chromosomes continue to condense
5) Spindle fibres attach to the cetromeres of the chromosomes
6) Spindle fibres pull on the centromeres, arranging them at the equator

19
Q

Anaphase

A

1) Links between sister chromatids break

2) The centromeres of sister chromatids move apart, pulled by the spindle fibres to the poles of the cell

20
Q

Telophase

A

1) Sister chromatids (now separate chromosomes) reach opposite poles
2) The chromosomes decondense
3) Nuclear envelope begin to form around the chromosomes at each pole
4) The spindle disappears

21
Q

Cytokenesis

A

The cell divides into 2 cells, either by the infolding of the cell surface membrane in animal cells, or by the formation of a new cell wall and cell surface membrane in plants

22
Q

Mitosis Stages

A

1) Interphase
2) Early Prophase
3) Late Prophase
4) Metaphase
5) Anaphase
6) Telophase
7) Cytokenesis

23
Q

Significance of Telomeres

A

1) Rich in base guanine G
2) Proposed that shortening of telomere is somehow connected to ageing process
3) Prevents loss of genes
4) Allows continual cell replication

24
Q

Stem Cells

A

cells can divide an unlimited number of times - each new cell has a potential to remain a stem cell or to differentiate into a specialised cell

25
Q

Totipotent

A

a cell that can give rise to all parts of embryo and adult eg. zygote formed by fertilisation - can develop into embryo & placenta

26
Q

Pluripotent

A

a cell that can give rise to many but not all parts of an organism eg. embryonic stem cells

27
Q

Multipotent

A

a cell that can give rise to few cell types eg. adult stem cells
- Undifferentiated cells can differentiate into number of different cell types eg. stem cells in bone marrow differentiate into blood cells - WBC, RBC, platelets

28
Q

Tumour

A

consists of a clone of cells identical to original mutated cell

29
Q

Carcinogen

A

Any agent that causes cancer and is described as carcinogenic

30
Q

Mutatic Agents

A
  • High fat diet
  • X-rays
  • Ionising radiation
  • Poor checking of chromatids (during interphase)
  • Carcinogen / smoking
  • Alcohol / drugs
  • Pollution
31
Q

Oncogene

A

cancer-causing genes

32
Q

Pro-oncogene

A

normal gene coding for protein that stimulates normal cell growth & division

33
Q

Tumor suppressor genes

A

Tumor suppressor genes are normal genes that slow down cell division, repair DNA mistakes, or tell cells when to die (a process known as apoptosis or programmed cell death). When tumor suppressor genes don’t work properly, cells can grow out of control, which can lead to cancer.