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My BIO DAT Prep > Cell Division > Flashcards

Cell Division Flashcards

1
Q

How many copies of paired chromosomes do human somatic cells have? How many total chromosomes do human somatic cells have?

A

23 copies of paired chromosomes
46 total chromosomes (23 maternal copies and 23 paternal copies)

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2
Q

Sister chromatids

A

Identical copies of replicated chromosomes

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3
Q

Homologous chromosomes

A

Two different copies of the same chromosome in a diploid organism

One copy is given by the mother and the other copy is given by the father

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4
Q

Kinetochores

A

Proteins on the sides of the centromeres that help microtubules pull sister chromatids apart during cell division
Extend from the centrosome and attach kinetochore on chromosomes

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5
Q

Centromere

A

Regions of DNA that link sister chromatids together in order to form a dyad

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6
Q

Somatic cells that contain two complete sets of chromosomes

A

Diploid

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7
Q

Non-homologous chromosomes

A

Chromosomes that do not contain the same genes
Example: human sex chromosomes (x and Y)

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8
Q

Gametocytes

A

diploid germ cells that help to create gametes, contains 2 complete sets of chromosomes

They can divide by mitosis to form more gametocytes (replenishing the parental germ line) or they can divide by meiosis to form gametes

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9
Q

G1 phase:

A
  • the cell physically grows and increases in size
  • lots of protein and ribosomes are synthesized
  • most variable in length of all phases depending on cell type
  • has a checkpoint: checks to see if cell is ready for DNA syntehsis
  • the cell will assess the conditions it finds itself in
    › favorable conditions: proceeds to S phase
    › unfavorable conditions: enters G0
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10
Q

What are some of the conditions in which a cell will enter G0 ?

A

• high surface area to volume (S/V) ratio
• high genome-to-volume (G/V) ratio
• insufficient nutrients
• contact inhibition
• lack of anchoring

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11
Q

S (synthesis) phase:

A
  • cell will replicate its genome in preparation for cell division
  • a new DNA molecule is replicated from the first, providing sister chromatid
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12
Q

Mitosis promoting factors (MPF)

A

Regulatory protein/enzyme that must be present in adequate amounts for mitosis to occur

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13
Q

Kinetochore microtubules

A

Extend from centrosomes and attach to kinetochores on chromosomes, holding onto the chromosomes

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14
Q

Astral microtubules

A

Extend from centromeres to the cell membrane to orient the spindle apparatus, also help in pulling the chromosomes apart during anaphase

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15
Q

Polar microtubules

A

Extend form the two centrosomes and connect with each other, they push the centrosomes to the opposite end of the cell which also aids in separating of the chromosomes during anaphase

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16
Q

What organelle are centrosomes located near?

A

The nucleus

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17
Q

What connects the mother centriole and daughter centriole to each centrosome?

A

Interconnecting fibers at a 90° angle

18
Q

Centrosomes

A

• Organelles found in an animal cells
• Contain a pair of centrioles
• Positioned at a angle of 90° within one another
• Act as MTOCs during cell division

19
Q

How is the basal body formed?

A

When the mother centriole attaches to the cell membrane

20
Q

Pericentriolar material

A

• Matrix of proteins that surround the centrioles
• The proteins play a role in microtubule nucleation and with securing microtubules to the centrioles

21
Q

What do centrioles determine in the cell?

A

Where the nucleus and other organelles are placed within the cell

22
Q

Karyotyping

A

Biological laboratory technique that allows scientists to visualize a cell’s chromosomes
Usually performed during metaphase

23
Q

What is the shortest step of mitosis?

A

Anaphase

24
Q

What phase of mitosis does cytokinesis begin animal cells? In plant cells?

A

Late anaphase in animal cells
Telophase in plant cells

25
Q

During cytokinesis in animal cells, what causes the contractile ring to get tighter and pinch the cell in two?

A

Myosin motors travel along the actin microfilaments and contract, pulling the plasma membrane toward the center of the cell —> this creates a contractile ring that gets tighter and eventually pinches into two cells

26
Q

Synaptonemal complex

A

A protein structure that forms between homologous chromosomes during synapsis. The complex is formed during the prophase of meiosis I

27
Q

Law of segregation

A

one member of each chromosome pair migrates to an opposite pole in anaphase I so that each gamete is haploid (each gamete is left with one copy of each allele

28
Q

Law of independent assortment

A

the migration of homologues within one pair of homologous chromosomes does not influence the migration of homologues of other homologous pairs

29
Q

what do viruses consist of?

A
  • nucleic acid: double or single stranded RNA or DNA
  • capsid: protein coat that encloses the nucleic acid
  • capsomeres: assemble to form the capsid
  • viral envelope: surround capsid of some viruses and incorperates phospholipids and proteins obtained from the cell membrane to the hsot
30
Q

what is a bacteriophage?

A

a virus that only attacks bacteria - usually specific to a type of cell via viral surface proteins binding to specific receptors on the host cell of the species

31
Q

What are the DNA repair mechanisms?

A

Proofreading, mismatch repair, excision repair

32
Q

DNA proofreading

A

DNA polymerase checks base pairs

33
Q

mismatch repair

A

enzymes repair the errors DNA polymerase missed - corrects missmatches between normal bases

34
Q

Excision repair

A

enzymes remove nucleotides damaged by mutagens
* nucleotide excision repair
* base excision repair:

35
Q

what occurs during prophase of mitosis?

A
  • nucleus disassembles
  • nucleolus diasappears
  • chromatin condense into chromosome
  • nuclear envelope breaks down
  • mitotic spindle form from the centrosomes
  • microtubules begin connecting to kinetochores
36
Q

what occurs during metaphase of mitosis?

A
  • chromosomes line up single file at the metaphase plate
  • spindle fibers attach to the kinetochore of each chromatid
  • centrosomes are at opposite poles of the cell
37
Q

what occurs during anaphase of mitosis?

A
  • cohension proteins binding the sister chromatids together break down
  • chromosomes pulled apart into 2 chromatids –> each chromatid is now a chromosome and the chromosome number doubles
  • microtubules shorten pulling chromosomes to opposite poles of the cell (dijunction)
  • non-kinetochore spindle fibers lengthen, elongating the cell
  • at the end of the phase: each pole has a complete set of chromosomes (same as original cell before replication)
38
Q

what occurs during telophase of mitosis?

A
  • nuclear envelope develops and surrounds each set of chromosomes
  • mitotic spindle breaks down
  • chromosomes decondense to chromatin
  • nucleoli reappear
39
Q

what occurs during cytokinesis of mitosis?

A
  • occurs during the end of anaphase
  • cleavage furrow forms in animal cells: involves shortening of actin and myosin microfilaments and the plasma membrane is pulled into the center of the cell
  • a cell plate forms in plant cells: involves vesicles from golgi bodies migrating and fusing to form a cell pate, the cell plate grows, merges w the plasma membrane, separating the 2 new cells
40
Q

what are the three events that allow for genetic variation?

A
  • crossing over during prophase I
  • independent assortment of homologues furing metaphase I
  • random joining of gametes
41
Q

surface to volume ratio:

A
  • as cells grow, volume grows much larger compared to surface area
  • large SA:V = no cell dividion because exchange across cell is easy
  • small SA:V = division to increase SA

My BIO DAT Prep (24 decks)

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