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Genetics > Sexual and Asexual Reproduction > Flashcards

Sexual and Asexual Reproduction Flashcards

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Biology 101 flashcards
1
Q

What is asexual reproduction?

A
  • reproduction without the fusion of gametes.
  • it involves one parent only.
  • offspring is identical to the parent
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2
Q

What are the main forms of asexual reproduction?

A

1) BINARY FISSION

2) MULTIPLE FISSION

3) BUDDING

4) FRAGMENTATION

5) VEGETATIVE PROPAGATION

6) SPORE FORING

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3
Q

What is sexual reproduction?

A
  • reproduction in which two gametes (sex cells) fuse to create a new offspring
  • offspring is genetically identical to its parents
  • two parents are involved
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4
Q

What are the advantages of sexual reproduction?

A
  • high genetic variability
  • facilitates adaptation
  • “speeds” up evolution
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5
Q

What are the disadvantages of sexual reproduction?

A
  • energy costly
  • courtship is time and resource consuming
  • usually sacrifices the fitness of one sex to the other
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6
Q

What are the advantages of asexual reproduction?

A
  • saves energy
  • courtship is not an issue
  • greatest increase in fitness for each individual
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7
Q

What are the disadvantages of asexual reproduction?

A
  • low genetic variability
  • adaptation to environments is difficult
  • “retards” evolution
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8
Q

What is the basis of asexual reproduction?

A

MITOSIS

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9
Q

What is the basis of sexual reproduction?

A

MEIOSIS (cell division- allowing for variety)

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10
Q

Explain the stages of mitosis.

A

INTERPHASE: G1, S, G2
MITOSIS:
- prophase (nuclear membrane dissolves)
- metaphase (mitotic spindles form, chromosomes condense, chromosomes align)
- anaphase (chromatids separate (daughter chromosomes))
- telophase (division of cells, cytoplasm begins to separate, nuclear membrane reforms))
CYTOKINESIS (division of cytoplasm)

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11
Q

What are the key points of mitosis?

A

During mitosis, a single cell divides and produces two identical daughter cells.
Each cell contains the same genetic material and chromosome number as the original cell.
One cell is maternal, the other is paternal.

  • each chromosome duplicates, to later undergo cytokinesis (division into 2) and still being identical
    2 sister chromatids duplicates into 4 sister chromatids. (1 chromosome —> 2 chromosomes)
  • two identical diploid cells are produced
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12
Q

What are homologous chromosomes?

A

chromosomes which are similar in shape, size and genetical information (position).

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13
Q

Explain meiosis.

A

Meiosis is a form of replication from which one parent cell divides into four non-identical haploid cells.
-prophase, metaphase, anaphase and telophase all occur twice.

  • amount of DNA in cells is reduced from diploid to haploid cells.
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14
Q

What are the differences between meiosis and mitosis?

A

meiosis:
- tetrad foration
- crossing over occurs
-

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15
Q

Describe the process of Meiosis I.

A

Prophase 1:
- choosomes become visible and condensed
- pairing between homologous chromosomes start
- crossing over occurs (providing genetic variability)
-

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16
Q

What does crossing over provide?

A

genetic variability.

there are 2 recombinant chromatids and 2 non-recombinant chromatids

17
Q

Explain metaphase 1

A
  • homologous chromosomes migrate to the middle plane fo the cell
  • spinde fibers attach to the centromeres
18
Q

Explain Anaphase 1

A
  • spindle fibres pull thehomologous chroosomes towards the opposite ends of the cell.
19
Q

Explain telophase I

A
  • first set of two daugther cells
20
Q

Explain metaphase II

A
  • reorganisation and preparation for the next division
21
Q

Exlain etaphase II

A
  • replicated chromosoes move towards teh middle plane
  • spindle fibres attach to the centrromeres
22
Q

explain anaphase II

A
  • seperation of sister chroatids (sister chroatids are not hoologous chromosoes)
  • migratin towards oposite sies
23
Q

Explain telophase II

A
  • second set of 2 haploid daughter cells
    total gametes produces: 4
24
Q

What is independent assortment?

A

members of the different pairs of hoologous chroosoes seperate randoly from each other.
- paternal and maternal chromosomes can switch sides.

Independent assortment produces variations in the combination of chromosomes in the gametes

25
Q

what is N=2^n
N=2^(n+k)
M=2^(n-1)

A

n= nuber of haploid cells
k= nuber of crossing over

26
Q

What is the biological significance of meiosis?

A
  • meiosis maintains the same chroosomes (n) number in the sexually reproducing organisms.
  • diploid cells produce haploid gametes which later fuse to produce haploid cells.
  • restricts the multiplication of chroosome number
  • maintains the satbility of the species
  • maternal and paternal genes get exchanged during crossing over
  • four unique haploid cells leads to variation in daughter cells
27
Q

Explain gametogenesis.

A

Gametogenesis is the process in which diploid precursor cells undergo meiotic division to becoe haploid gametes.

males: spermatogenesis
females: oogenesis

process occurs in the gonads

steps
- itotic division and cell growth of precursor germ cells
- two meiotic divisions to produce haploid daughter cells
- differentiation of the haploid daughter cells to produce functional gametes

28
Q

Compare and contrast spermatogenesis and oogenesis.

Location:
Meiotic divisions:
Germ line epithelium:
Number of gamtetes produces:
Size of gamtetes produced:
Duration:
Onset:
Release:
End:

A

Spermatogenesis:
Location: occurs entirely in the testes
Meiotic divisions: equal division of cells
Germ line epithelium: involved in gamete production
Number of gamtetes produced: 4 gametes
Size of gamtetes produced: sperm are smaller than speratocytes
Duration: uninterrupted process
Onset: begins t puberty
Release: continuous
End: lifelong (reduces with age)

Oogenesis:
Location: occurs mostly in the ovaries
Meiotic divisions: unequal divisions of the cytoplasm
Germ line epithelium: not involved in the gamete production
Number of gamtetes produced: one (+2/3 polar bodies)
Size of gamtetes produced: ova is larger than oocytes
Duration: in arrested stages
Onset: begins in the fetus (pre-natal)
Release: monthly fro puberty (menstrual cycle)
End: terminates with menopause

29
Q

Explain the different parts of prophase I in meiosis I.

A

LEPTOTENE: “BOUQUETE STAGE”
- chromosomes become more uncoiled (they resemble a long thread like shape)

ZYGOTENE / SYNAPTOTENE: pairing of homologous chromosomes (called SYNAPSIS)

PACHYTENE: pair of chromosomes become twisted spirally around each other, and cannot be distinguished seperately.
they are termed “BIVALENTS”

Genetics (3 decks)

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