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Biology AS Level > MITOSIS > Flashcards

MITOSIS Flashcards

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1
Q

Outline role of microtubules in mitosis (4)

A
  1. Forms part of spindle fibres
  2. Attachment to centromeres
  3. Movement of sister chromatids to opposite poles
  4. Spindle fibres shortening at anaphase
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2
Q

Explain how terms monomer + macromolecule can be applied to tubulin

A
  • MONOMER = protein/tubulin composed of AA joined together by peptide bonds
  • MACROMOL= Large molecule composed of amino acids/ polypeptide chains like protein
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3
Q

Explain why it’s important that daughter cells produced during mitotic cycle in humans are genetically identical

A
  • Same number of chromosome as parent cell
  • cell would be rejected if genetically diff
  • role of immune system in removing genetically different cells
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4
Q

Name 2 factors that increase chance cancer cells will develop

A
  • UV/X rays
  • ionizing radiation + gamma rays
  • Radon
  • Viruses;HPV + HIV
  • Genetic/hereditary factors
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5
Q

Describe what’s is occur in in telophase

A
  1. Chromosomes uncoil/decondense
  2. Chromes become chromatin + enters interphase
  3. Spindle fibres break down/ microtubule disassemble
  4. Nuclear envelope reforms
  5. Nucleolus/ forms
  6. Cell membrane furrows
  7. Cleavage furrow develops = fusion and divides cell into 2
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6
Q

Describe events that occur during prophase

A
  1. Chromatin/chormomes condense + become visible
  2. Supercooling = two sister chromatids joined together at centromere
  3. Nucleolus diseapers
  4. Nucleur enevlope disables/breaks down
  5. Centrioles move to poles
  6. Spindle fibres start to form
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7
Q

Suggest why some cells appear empty w no nucleus or chromomes under miscroscope

A
  • not sectioned to include nucleus
  • did not take up stain/not stained
  • cells dead
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8
Q

Describe what occurs in cytokinesis in plant cell

A
  1. Cell plate forms across equator of cell = made from vesicles
    - Cell wall/cellulose laid down
  2. Cytoplasm divided into two = 2 genetically identical Daughter cells
  3. organelles shared out e.g vesicles transported to equator
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9
Q

Suggest role of meristaimatic cell + explain features that aid it to carry out its role

A
  1. Form cells that can differentiate/totipotent
  2. Cell replacement/repair/growth
  3. Divides to give more/continuous supply of stem cells
  4. Stem cells are undifferentiated = not specialized
  5. Able to divide/undergo mitosis = can replicate
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10
Q

In cell cycle, more mRNA produced in G1 phase than during mitosis,m suggest why

A
  1. More proteins/polypeptides made
  2. Proteins required for growth/to provide protein for DNA synthesis
  3. During mitosis DNA highly condensed
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11
Q

State substances used to synthesizes DNA during S phase

A
  1. ATP
  2. Activated free nucleotides
  3. DNA polymerase
  4. DNA ligase
  5. DNA helicase
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12
Q

Describe behaviour of nuclear envelope during mitosis

A
  1. Breaks down in prophase
  2. Reforms after anaphase IN telophase
  3. Reforms vesicles/vesicles fuse to form new membrane
  4. Reforms around both sets of daughter chromosomes
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13
Q

FUnction of telomerase

A
  • permit continued replication = adds bases to ends of chromosomes = continued cell division = get around haeflick limit
  • Acts as buffer so genes aren’t lost from ends of chromosomes during DNA replication/ no fusion
  • Made of non coding DNA
  • Prevents loss of genes + Caps ends of chromosomes
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14
Q

Why is continued replication bad +s shortening of telomeres

A
  • Telomeres regulate Cell division+ protect genes
  • get shorter + gene exposure + damages chromosome = cannot replicate
  • Uncontrollable division + mitosis = mutation —> cancer
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15
Q

Two cells containing telomerase

A

Stem cells and lymphocytes

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16
Q

Totipotent STEM cells

A

TOTI= can differentiate into any type of cell e.g zygote
- all genes active
- exposed to chemicals + gene switched off

17
Q

Haematopioetic stem cells + tissue replacement

A
  • Multipotent stem cells and differentiate into ANY other type of blood cells (found in bone marrow)

Stem cell therapy = introduction of new adult stem cells into damaged tissue to treat disease/injury
Tissue replacement = used fro transplants + used embryonic stem cells but have to destroy embryo (unethical)

18
Q

role of centrioles during mitosis

A

1) act as MTOCs
2) assemble/form spindle fibres during prophase
3) contraction of spindle fibres during anaphase separates sister chromatids

19
Q

Describe how the spindle is involved during mitosis.

A
  1. Prophase: attach to centromere of each chromosome
  2. Metaphase: arrange chromosomes at equator/metaphase plate of cell
  3. Anaphase: spindle fibres contract and pull apart sister chromatids to poles of cell
  4. Telophase: elongate to push nuclei apart
20
Q

Differences in plant and animal cells mitosis

A

1) plant cells don’t have any visible centriole or aster
2) daughter cells get separated by cell plate in plants

21
Q

metaphase

A
  • Spindle fibers extend fully from centrosomes
  • Spindle fibres reach chromosomes + attach to centromeres
  • chromosomes line up across equatot/metaphse plate
22
Q

Anaphase

A
  • centromeres have divided
  • Sister chromatids move to opp poles by spindle fibres
  • sister chromatids at the centromere + shorten
  • NO NUCLEAR ENVELOPE
23
Q

Chromatin

A

Combination of DNA and proteins

24
Q

G1 phase

A
  • growth
  • transcription + translsation = proteins synthesised/RNA
  • increase in vol of cytoplasm
25
Q

S phase

A
  • doubles number of strands
  • Semi conservative replication
  • chromosome becomes two chromatids
26
Q

M phase (mitosis)

A

Production of genetically identical cells
- growth
- cell replacement
- repair of tissues
- asexual reproduction

27
Q

CentroMERE

A
  • Site of attachment of spindle microtubules
  • Each metaphase chromosome has two kinetochores at its centromere
28
Q

CentroSOME

A
  • Present at the poles of the spindle
  • An organelle found in animal cells that acts as an MTOC for construction of the spindle
29
Q

Chemotherapy

A

-cancer treatment preventing DNA replication/inhibits METAPHASE–> damaging spindle fibres
- chromosomes CANNOT travel to the poles of the cell

30
Q

G2

A

Proof checking + cell continues growing
- if CBP doenst occur = enzymes will remove bases + complimentry bases pairs will form
- DNA normal aagin

31
Q

Pluripotent STEM cell

A
  • undiffrentiated cells
  • some genes switched off/deactivated
  • can differentiate into specialised cells BUT NOT TOTIPOTENT/embryonic
32
Q

Describe how fertleised egg is source of Pluripotent STEM cell

A
  • fertelised egg allowes to divide 7erval times = blastocyst
  • cells in inner cell mass = pluripotent
  • IVF
33
Q

explain importance of DNA replication during development of zygote into blastocyst

A
  • zygote divides by mitosis = blastocyst
  • identical copies of DNA
  • all cells in blastocyst diploid
  • so when mitochondra divide will have copy of DNA
34
Q

Describe root tip squash so chromosomes can be seen

A
  • ## cut root tip + add HCL +orcein stain

Biology AS Level (12 decks)

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