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MANA 1513 > Session 6 - Introduction To Embryology And Gametogenesis > Flashcards

Session 6 - Introduction To Embryology And Gametogenesis Flashcards

1
Q

What happens during interphase in mitosis?

A
  1. DNA replicates
  2. Chromatin network coils, contracts and condenses to prepare for prophase
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2
Q

What happens during prophase in mitosis?

A
  1. Chromosome are present
  2. Cytoskeleton breaks down
  3. Centrioles move to opposite poles
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3
Q

What happens during prometaphase in mitosis?

A
  1. Nuclear membrane breaks down
  2. Microtubules attach to centrioles to centromeres
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4
Q

What happens during metaphase in mitosis?

A
  1. Chromosomes align at the middle of the cell
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5
Q

What happens during anaphase in mitosis?

A
  1. Chromosome pairs split and sister chromatids move to opposite sides
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6
Q

What happens during telophase in mitosis?

A
  1. Chromatids uncoil and lengthen
  2. New membranes form
  3. Cytoplasm splits
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7
Q

What happens during cytokinesis in mitosis?

A
  1. A ring around centre shrinks and splits cell into two
  2. Each daughter cell has the same number of chromosomes as the parent cell
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8
Q

What happens during interphase in meiosis?

A
  1. DNA is replicated
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9
Q

What happens in prophase 1?

A
  1. Homologous chromosome align and pair up
  2. There is fusion of homologous chromosomes at the chiasma and there is a possibility of crossing over taking place which leads to genetic variation
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10
Q

What happens during prometaphase 1?

A
  1. Nuclear membrane disappears
  2. Microtubules attach centrioles to centromeres
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11
Q

What happens during metaphase 1?

A
  1. Chromosomes align at the equator and the law of independent assortments comes into effect
  2. Spindle apparatus form
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12
Q

What happens during anaphase 1?

A

Pairs of homologous chromosomes split and move to the opposite poles

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13
Q

What happens during telophase 1?

A
  1. New nuclear membrane forms
  2. Cytokinesis cleaves cell in 2
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14
Q

What happens during prophase 2?

A
  1. Chromatids condense
  2. Nuclear membrane disappears
  3. Centrioles move to opposite poles
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15
Q

What happens during metaphase 2?

A

Chromosomes align at the equator of the cell

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16
Q

What happens during anaphase 2?

A

Chromosomes split and sister chromatids move to the opposite poles

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17
Q

What happens during telophase 2?

A

Sister chromatids reach opposite poles and nuclear membrane forms.

Cytokinesis cleaves each cell into 2

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18
Q

What is the end result of meiosis?

A
  1. 4 non-identical daughter cells each with 23 chromosomes making them haploid cells.
19
Q

What is cell trisomy?

A

When a cell has one extra chromosome

20
Q

What is monosomy?

A

When a cell have one missing chromosome

21
Q

What is non-disjunction?

A

Ineffective separation of chromosomes or chromatids during meiosis 1 or 2

22
Q

What are the consequences and chromosomal abnormalities?

A
  1. Birth defects
  2. Spontaneous abortions
23
Q

What are the 2 types of chromosomal abnormalities?

A
  1. Structural
  2. Numerical
24
Q

What are the possible results of non-disjunction of sex chromosomes?

A
  1. XXX
  2. XXY or XXXY
  3. XO
  4. YO
25
Q

Explain the condition of XXX

A
  1. This is as a result of non-disjunction of the sex chromosomes.
  2. It is called Metafemale or Triple X syndrome.
  3. The individual has a normal female appearance and may exhibit some mental disability
26
Q

Explain the condition XXY or XXXY

A
  1. It is as a result of non0disjunction of sex chromosomes
  2. It is called Klinefelter syndrome
  3. The individual is a sterile male and their body is feminised
27
Q

Explain the condition XO

A
  1. It is as a result of non-disjunction of sex chromosomes
  2. It is called Turner’s syndrome or Monosomy X
  3. The individual is a female who exhibits stunted growth and a webbed neck
28
Q

Explain the condition YO.

A

This is not a viable result and the X chromosome is needed. This results in spontaneous abortion.

29
Q

Lis the types of structural chromosomal abnormalities.

A
  1. Translocations
  2. Insertions
  3. Deletions
  4. Duplications
  5. Inversions
  6. Isochromosomes
  7. Dicentric chromosomes
30
Q

Explain the structural chromosomal abnormality of translocations.

A
  1. This occurs when a piece of a chromosome breaks off and attaches to another chromosome.
  2. They are often linked to the development of cancer, especially leukaemia.
31
Q

What are the two classification types of translocations?

A
  1. Balanced and unbalanced
  2. Reciprocal and nonreciprocal/Robertsonian
32
Q

What does the Balanced/Unbalance translocation classification entail?

A
  1. Balanced - genetic material is neither lost or gained
  2. Unbalanced - genetic material is lost of gained
33
Q

What does the Reciprocal/Non-reciprocal translocations classification entail?

A

Reciprocal - parts of chromosomes fuse to each other

Non-reciprocal/Robertsonian - whole chromosomes fuse with each other

34
Q

Explain the structural chromosomal abnormality of Insertions.

A
  1. A piece of a chromosome breaks off and attaches to another chromosome hence they are sometimes considered as translocations.
  2. Linked to Tay-Sachs which is 4 base insertion in gene
35
Q

Explain the structural chromosomal abnormality of deletions.

A
  1. A piece of chromosome breaks off and degenerates
  2. Size of lost part can range from a few genes to a whole chromosome arm
  3. Linked to Prader-Willi syndrome
36
Q

Explain the structural chromosomal abnormality of duplications.

A
  1. This occurs when a piece of the chromosome is produced more than once on the same chromosome.
37
Q

Explain the structural chromosomal abnormality of inversions.

A
  1. A piece of chromosome breaks away and reattaches to same chromosome but upside down
  2. Is harmless but causes disruptions in gene sequences near breaks
  3. Linked to haemophilia
38
Q

What are the two kinds of chromosomal inversions?

A
  1. Pericentric - broken part includes centromere
  2. Paracentric - broken part consists of only parts of either arm
39
Q

Explain the structural chromosomal abnormality of Isochromosomes.

A
  1. These are chromosomes with 2 identical arms
  2. Are a result of abnormal separation of chromatids or deletion of 1 arm and duplication of other
  3. Mostly results in some form of neoplasia and sometimes Turner syndrome.
40
Q

Explain the structural chromosomal abnormality of ring chromosomes

A
  1. Ends of chromosome or of broken part fuse to form circular structure
  2. They are found in nearly all human chromosomes
  3. Ring 20 syndrome (epilepsy)
41
Q

What are the diagnostician techniques for detection of chromosome abnormalities?

A
  1. Amniocentesis - sampling cells in amniotic fluid
  2. Chorionic villi sampling
42
Q

Explain the process of spermatogenesis

A
  1. Starts with with diploid primary germ cells called spermatogonia which duplicate via mitosis
  2. Spermatogonia mature into diploid primary spermatocytes
  3. Primary spermatocytes undergo meiosis 1 and become haploid secondary spermatocytes
  4. The haploid secondary spermatocytes undergo meiosis 2 and become haploid spermatids
  5. Spermatids undergo spermiogenesis to convert to spermatozoa
43
Q

Describe the process of spermiogenesis

A
  1. The rounded shape of the spermatids elongates to form the head, midpiece and tail.
  2. The cytoplasm sheds
  3. Nucleus condenses and is packed into the head
  4. Mitochondria move to the first part of the tail
  5. The acrosome forms at the tip of the head
44
Q

Describe the process of oogenesis

A
  1. Starts with diploid primordial germ cells called oogonia which multiply by mitosis
  2. Oogonia start meiosis 1 at week 12 of embryonic development and arrest at prophase 1
  3. During meiosis 1, the oogonia become diploid primary oocytes
  4. At puberty the primary oocyte completes meiosis 1 and becomes a haploid secondary oocyte with a polar body
  5. Meiosis 2 begins at ovulation and stops at metaphase 2 and will only continue if the secondary oocyte is fertilised.
  6. The secondary oocyte becomes an ovum

MANA 1513 (17 decks)

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