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BIO 100A > Cell division and reproduction > Flashcards

Cell division and reproduction Flashcards

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Biology 101 flashcards
1
Q

What is cell division? differentiate between the two types of reproduction.

A

Cell division is the reproduction of cells from pre-exisiting cells.

Asexual reproduction
-Producing offspring that are all genetic copies of the parent and identical to each other (clones)

Sexual reproduction
- Producing offsprings that are genetically diverse from the parent.

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2
Q

Differentiate between a chromosome, chromatid and chromatin.

A

1.When genetic material is densely packed, it is referred to as chromosome.This structure is only seen in a cell actively undergoing the cell cycle.

  1. When genetic material is loosely packed , it is referred to as chromatin.This is the typical structure of DNA when the cell is not preparing for division.
  2. When a chromosome duplicates itself, it creates two sister chromatids. at the point where the DNA is duplicated.

The chromatids later condense to form chromosomes.

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3
Q

Differentiate between prokaryotes and eukaryotes.

A

Prokaryotes ( bacteria and archea)
-fewer organelles and genetic material
- Have fewer genes, their genes are all packed within a single circular DNA molecule

Eukaryotes (every other organism)
-more organelles and genetic material
-more genes and they are packed into multiple chromosomes.

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4
Q

Explain prokaryotic reproduction.

A

Prokaryotic cells reproduce asexually by binary fission.

  1. The duplication of the single chromosome and the copies begin to move apart.
  2. More elongation leads to the plasma membrane pinching itself.
  3. More cell wall is made and divides the parent cell into two daughter cells.
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5
Q

What is a centromere?

A

When a chromosome is duplicated during the cell division process, the original and duplicate are referred to as sister chromatids and are attached together through the centromere.

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6
Q

What is the cell cycle?

A

The cell cycle is an ordered sequence of events that run from the time a cell is first formed from a dividing parent cell, until its own division into two cells. It alternates between growing and dividing.

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7
Q

All cells divide at the same rate. True or false?

A

False.Some cells divide every day (ex: blood cells, skin cells), while others never do (mature muscle cells (heart), nerve cells.

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8
Q

What are the two major events in a cell cycle?

A

Interphase: period of cellular growth
Cell makes more cytoplasm, organelles, and proteins needed for two resulting cells
-Chromosomes duplicate
-High metabolic rate
-Lasts ~90% of the cell cycle

Mitotic phase: period of cell division
-Mitosis is division of the nucleus and all of its contents
-Cytokinesis: division of the cytoplasm and all of its contents

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9
Q

What are the sub-phases of interphase?

A

G1: first gap, period of growth
S: synthesis phase in which chromosomes are duplicated
G2: second gap, period of additional growth and preparation of mitosis

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10
Q

Explain the process of mitosis?

A

Mitosis is the distribution of duplicated chromosomes into two new daughter nuclei.

  1. The chromatin is coiled and a mitotic spindle of mictrotubules is formed and moves the chromosomes to the middle of the cell.
  2. Centrosomes will anchor the mitotic spindle at opposite ends and pull apart the sister chromatids, thereby seperating them
  3. The sister chromatids are moved to opposite poles, where the two new nuclei is formed.
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11
Q

State all the stages of the cell cycle?

A

Interphase, prophase, prometaphase, metaphase, anaphase, telophase and cytokinesis.

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12
Q

What are the events of the prophase stage?

A
  1. In the nucleus, the chromatin begins to condense, making the sister chromatids more tightly packed and visible.
  2. In the cytoplasm, centrosomes that are moving away from each other begin to form microtubules.
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13
Q

What are the events of prometaphase?

A
  1. The nuclear membrane begin to break down and dissapper.
  2. The centrosomes reach their opposite poles and the mitotic spinndle attaches to the sister chromatids at the kinetohcore. This attachment pushes them to the centre of the cell.
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14
Q

What are the events of the metaphase stage?

A
  1. The mitotic spindle is attached at the kinetochore to the chromatids.
  2. The sister chromatids have reached the centre of the cell at the metaphase plate.
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15
Q

What are the events of the anaphase stage?

A
  1. The centromere comes apart, seperating the sister chromatids into chromosomes
  2. Motor proteins move along the mitotic spindle and pull the chromosomes to opposite poles.
  3. Any spindle attached to a chromosome shortens, and there are now an equal number of chromosomes on each end.
  4. Elongation begins as the chromosomes are pulled apart.
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16
Q

What are the events of the telophase and cytokinesis?

A

Teleophase
1. The elongation that began during anaphase continues.
2. Nuclear membrane is formed around the chromosomes.
3. The chromatin begins to uncoil and mitotic spindle disappears.

Cytokinesis
1. The seperation of the cytoplasm.
2. In animal cells, there is a cleavage furrow forms. In plants, a cell plate is formed.

17
Q

Differentiate between mitosis and meiosis?

A

Mitosis is a cell divison in which one dipolid parent divides into 2 dipolid cells.

Meiosis is a cell division that takes place during sexual reproduction, one dipoloid cell divides into 4 haploid cells.

18
Q

Define somatic cell, gametes, sex chromosomes, autosomoes and locus.

A

1.Somatic cell: a typical body cell
Humans 46 chromosomes (2 of each chromosome)

  1. Gametes: sperm and egg cells
    Humans 23 chromosomes (1 of each chromosome)
  2. Locus: specific location on a chromosome
    Sex chromosomes: chromosomes defining sex (X and Y)
    Humans typically have 2
  3. Autosomes: all chromosomes other than sex chromosomes
    Humans typically have 44
19
Q

Meiosis occurs only in reproductive organs/cells, true or false?

A

True.

20
Q

What is meiosis 1 and meiosis 2?

A

Meiosis 1 invloves the seperation of each of the members of the homologous pair, then each of them will produce two daughter cells with one set of chromosomes respectively.

Meiosis 2 is essentialy mitosis. It involves the seperation of the sister chromatids resulting in 4 haploid cells.

21
Q

State the cell cycle for meiosis sexual reproduction.

A

Interphase, meiosis 1 which is divided into prophase 1, metaphase 1, anaphase 1 and telophase 1. Telophase 1 and cytokinesis. Meiosis 2 : prophase 2, metaphase 2, anaphase 2, telophase 2 and cytokinesis.

22
Q

Describe the events during prophase 1.

A

Prophase I:
-homologous chromosomes come together
-2 pairs together = tetrad
-Crossing over occurs(swapping genetic material)
-Chromosomes begin to condense
-Nuclear envelope breaks and spindles start reaching for chromosomes

23
Q

Describe the events at metaphase 1 and anaphase 1.

A

Metaphase I and Anaphase I are very similar processes as you see in mitosis

The main difference is that instead of all duplicated chromosomes aligning together in metaphase, homologous chromosomes pair up at the metaphase plate

Each daughter cell will only get one of the homologous chromosomes.

24
Q

Describe the events during telophase 1 and cytokinesis 1?

A

Telophase I: chromosome reach poles of the cell, with each pole now containing one haploid set of chromosomes

Cytokinesis : Occurring simultaneously with telophase I, the cell separates into two haploid daughter cells

25
Q

What is chiasma?

A

The point of crossing over is called the chiasma.

26
Q

Describe the events of meiosis 2.

A

The sister chromatids seperate, each going to a different pole.

The result will be two parental chromosomes that match the orginals and two recombinant chromosomes.

27
Q

An abnormal chromosome count is the result of what? how does it occur?

A

An abnormal chromosome count is the result of nondisjunction, which can result from:-

  1. The failure of a pair of homologous chromosomes to separate during meiosis I
  2. Or the failure of sister chromatids to separate during meiosis I I
28
Q

Abnormal numbers of sex chromosomes affect survival. True or false?

A

False,Abnormal numbers of sex chromosomes do no usually affect survival

29
Q

What are the different alterations of chromosome structure?

A
  1. Deletion : A segment of chromosome is removed.
  2. Insertion : A segment of chromosome is removed and then reinserted opposite to its original orientation.
  3. Duplication : A segment of chromosome is copied and inserted into the homologous chromosome.
  4. Reciprocal translocation :Segments of two non-homologous chromosomes swap locations with each other

BIO 100A (30 decks)

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