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Biology 1 > Mitosis > Flashcards

Mitosis Flashcards

1
Q

What feature best distinguishes living things from non-living matter?

A

The ability to reproduce, which is based on cell division.

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2
Q

What is the genome?

A

A circular DNA molecule (constitutes all the DNA of a cell).

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3
Q

How do bacteria divide?

A

By binary fission

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4
Q

Describe the concept of binary fission

A
  • The single, circular bacterial chromosome is replicated (begins at origin of replication and proceeds bidirectionally).
  • New chromosomes are at the opposite ends of the cell
  • A septum forms to divide the cell into 2.
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5
Q

How is DNA arranged in the cells?

A

There are usually multiple DNA molecules (may be only one), which are packaged into chromosomes.

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6
Q

What cells perform mitosis?

A

All of them.

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7
Q

What are the major organelles involved in cell division?

A

Centrioles (assembly/organisation of mircotubules), cell membrane, cytoplasm, nucleus, nuclear envelope, nucleolus.

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8
Q

What are chromatin (including composition and shape)?

A

Dark material containing DNA (40%) and proteins (60%). Long, has to be condensed to fit into nucleus.

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9
Q

What is the chromatid structure?

A

Chromatin is coiled around proteins. Every 200 nucleotides coiled around 8 histone proteins.

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10
Q

What makes the nucleosome?

A

Histones and DNA

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11
Q

What is the selenoid?

A

A structure that nucleosomes are further compacted into.

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12
Q

How many chromosomes do Eukaryotes generally have? How many do humans have?

A

Generally between 10 and 50. Humans have 46.

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13
Q

How many different kinds of chromosomes do human have? How many sets?

A

23 different kinds of chromosomes. 2 sets of 23 chromosomes (one from the father and one from the mother).

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14
Q

What is a haploid number of chromosomes (n)?

A

Complete set of chromosomes necessary to define an organism. For humans, n=23.

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15
Q

What is a diploid number of chromosomes (2n)?

A

Reflects the equal contribution of each parent. For humans, 2n=46.

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16
Q

How are maternal and paternal sets called?

A

Homologous chromosomes.

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17
Q

What happens in sexual reproduction?

A

The sperm cell penetrates the egg cell and their nuclei fuse. They form a single nucleus containing 1 complete set of 23 chromosomes from each parent.

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18
Q

How do cell grow (number wise)?

A

Initial divides into 2, the 2 into 4, etc.

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19
Q

How is called the process prior to each division process in which the original genetic info is copied?

A

DNA replication

20
Q

What is the cell cycle (beginning and end)?

A

Series of events that occur in nearly every cell over its life span. Starts when daughter cells are produced by division of parent cells. Ends when daughter cells complete their development and divide themselves.

21
Q

What consists of most of a cell’s “life span”?

A

Cell growth and maturation.

22
Q

How long does the cell cycle last in mammalian cells (and how long for the mitosis phase)?

A

Approximately 24 hours. Usually 1 hour for mitosis.

23
Q

What are the three cell cycle phases?

A

Interphase, mitosis, and cytokinesis.

24
Q

What are the three phases of the interphase?

A

G1 phase, S phase, and G2 phase

25
Q

What is the G1 phase (beginning, end characteristics)?

A
  • Begins when D-cells formed.
  • Period of active growth. Size increases.
  • Synthesis of new organelles.
  • Eventually reaches mature size for cell type
26
Q

How are D-cells right after division?

A

They have a complete copy of the parent genetic info but only 1/2 of the cytoplasm+organelles of the parent.

27
Q

What is the s phase?

A

Synthesis phase. Chromosomes (and hence DNA) are copied for the next division.
An EXACT COPY of each chromosoms within the cell nucleus is produced.
Sister chromatids held together by cohesins.

28
Q

How are the copied chromosomes called?

A

Sister chromatids.

29
Q

What is the visible point of constriction on a chromosome?

A

The centromere

30
Q

How are sister chromatids attached?

A

At the centromere by complex proteins called cohesins.

31
Q

What are kinetochores and what are they used for?

A

Disclike structure at the outside portion of the centromere. Serve as attachment sites for microtubules necessary to separate chromosomes during cell division.

32
Q

What is the G2 phase?

A

Cell size increases slightly. Prep for mitotic phase.
In animals, the pair of centrioles duplicate. Tubulin (component of microtubules) is largely produced. Sister chromatids shorten.

33
Q

What is the mitotic phase and what are its phases?

A

Phase associated to the SORTING and DISTRIBUTION of the copies of chromosomes to each developping D-cell.

Phases are prophase, metaphase, anaphase, telophase (PMAT).

34
Q

What is the mitotic spindle?

A

Apparatus of microtubules that controls chromosome movement during mitosis.

35
Q

What happens in the prophase?

A

Condensation of chromosomes continues. Cytoskeleton disassembled. Two centrioles move to opposite poles of cell to form miotic spindle. Nuclear enveloppe and nucleolus disappear. Golgi and endoplasmic reticulum are dispersed.

36
Q

In what phase do Individual condensed chromosomes first become visible under light microscope?

A

Prophase

37
Q

How do chromosomes appear in prophase?

A

Like 2 sister chromatids held together at centromere.

38
Q

What happens in prometaphase

A

Microtubules attach to kinetochores. Each sister chromatid attached to opposite pole. Microtubules start to move the sister chromatids toward midline of cell.

39
Q

What happens in metaphase (and when does it start)?

A

Begins when the sister chromatids are aligned along the cell’s midline. Spindle fibers still attached to centromere (kinetochores). Chromosomes under tension.

40
Q

What happens in anaphase?

A

Spindle fibers start to contract. Pull toward opposite ends of cell. Centromeres break and chromatids separate (cohesins desintegrates). One copy of each pair of chromatids go to each end. Kinetochores pulled apart (A) and poles move apart (B).

41
Q

What happens in telophase?

A

Sister chromatids (one copy) present at each end of cell. Spindle disassembles and components used to make cytoskeleton. Nuclear envelope form around each set of chromatid (now called chromosome… no longer attached at centromere). Nucleolus reappears. Golgi and endoplasmic reticulum reform.

42
Q

What happens in the cytokinesis phase for animal and plant (not part of mitotic phase)?

A

Animals: cleavage furrows pinches cell in half
Plant: cell plate forms to divide the cell.
Each (2) D-cell with copy of genetic info of parent enters G1 and cel cycle begins again.

43
Q

How is mitosis in plant cells different?

A

No centrioles. Presence of centrosomes, spindle fibers do form.
Cell is not pinched in cytokinesis. D- cells separated by a cell plate formed by Golgi derived vesiles.

44
Q

How is cytokinesis different for some Fungi and Protists?

A

Nuclear envelope does not dissolve. Mitosis within nucleus. Division of nucleus with cytokinesis.

45
Q

How is the resting phase (pause) before G1 called?

A

G _0 phase. Most animal cells are in this phase.

46
Q

What is aster?

A

Radical arrangement where chromosomes are at the poles?

Biology 1 (13 decks)

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