Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Genetics & Evolutionary Biology > Chromosome Inheritance > Flashcards

Chromosome Inheritance Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

How can the number of chromosomes in any living thing be described?

A

An even multiple of a basic number. Eg Humans:
• Basic number is 23 (22 pairs of autosomal and 1 pair sex chromosomes)
• Diploid genome (2n) is 46: most somatic cells
• Sperm and oocytes, defines the haploid genome (n)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Are Haploid chromosomes the same number in all species?

A
  • No haploid chromosome number varies greatly between species
  • Average is 10-40
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How can you tell from a punnet square whether it is incomplete dominance and co dominance

A

when incomplete there is less of the dominant gene but when codominant then there are the same amount of both

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What was the first study after Mendel which provided evidence for the principle of segregation and independent assortment?

A

Studies on the inheritance of a sex-linked trait in Drosophila (genus of fly) provided the first evidence that the meiotic behaviour of chromosomes is the basis for Mendel’s Principles of Segregation and Independent Assortment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What evidence was found that proved Mendel’s principles?

A
  • Three experiments performed by Thomas Morgan and colleagues
  • In these experiment the first generations that were used had different eye colour. For example the first experiment started with a red, eyed female and a white eyed male.
  • Based on these three experiments the data showed that the gene for eye colour was linked to the X chromosome.
  • This proved that X and Y are morphologically distinct from each other and the autosomes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is an autosome?

A

Any chromosome that is not a sex chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is non-disjunction?

A

The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How was non-disjunction discovered?

A
  • Calvin Bridges examined the genotype of Drosophila (by studying the chromosome composition) of “exceptional” (unusual) red eyed males and “exceptional” white-eyed females
  • These studies verified that sex-chromosomes existed
  • Bridge’s called this anomaly non-disjunction because it involved failure of the chromosomes to disjoin during one of the meiotic divisions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Draw an example of the Drosophila non-disjunction hereditary chart.

A

https://docs.google.com/document/d/1Nzo4FTzXCbwOZjpoc_J_4IF3gsOXPcoyC2BowELmx0U/edit?usp=sharing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens when non-disjunction occurs?

A

When non-disjunction happens it means that the chromosomes that would usually separate during meiosis would stay together and be put inside the egg cell of the female. This means that the offspring would either have two x chromosomes before fertilisation or none at all.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Where in the meiosis process does non-disjunction occur?

A

It can occur in Meiosis 1 or Meiosis 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Can non-disjunction occur in Mitosis?

A

Yes, non-disjunction can occur in any cell reproduction because it involved the separation of sister chromatids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Draw a diagram outlining the different forms of non-disjunction in meiosis and mitosis.

A

https://docs.google.com/document/d/1Nzo4FTzXCbwOZjpoc_J_4IF3gsOXPcoyC2BowELmx0U/edit?usp=sharing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are X-linked genes?

A
  • Genes located on the X chromosome

- Also called sex-linked genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the chromosome theory of inheritance?

A

Boveri and Sutton’s chromosome theory of inheritance states that genes are found at specific locations on chromosomes, and that the behavior of chromosomes during meiosis can explain Mendel’s laws of inheritance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What was one of the most important things in developing the chromosome theory of inheritance?

A

Study of inheritance of characteristics whose genes lie on the X chromosome was instrumental in developing the chromosomal theory of inheritance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are genes positioned in chromosomes?

A

Genes are located on chromosomes in a linear array

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Draw a diagram of a chromosomes and label examples of different genes that may be found on it.

A

https://docs.google.com/document/d/1Nzo4FTzXCbwOZjpoc_J_4IF3gsOXPcoyC2BowELmx0U/edit?usp=sharing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why are sex-linked mutations some of the easiest to detect?

A

They show up immediately in hemizygous males

20
Q

Why are recessive x-linked traits more common in males

A

In humans, recessive X-linked traits more commonly appear in males as they only need to inherit one recessive allele for the recessive phenotype to show

21
Q

What are Homologous chromosomes?

A

Chromosome pairs (one from each parent) that are similar in length, gene position, and centromere location. The position of the genes on each homologous chromosome is the same. However, the genes may contain different alleles

22
Q

What is the pseudo autosomal region?

A

There are some homologous genes on both the X and Y chromosomes that are mostly located at the ends of the arms (of the chromosomes).

23
Q

Why is the pseudo autosomal region more important for males?

A
  • Alleles for the homologous genes are inherited in a similar manner to autosomal alleles.
  • In males, the pseudo-autosomal genes seem to mediate pairing of the X and Y chromosomes during mitosis and meiosis
24
Q

What is an example of an x-linked disorder in humans that is well known because of its affect on royal bloodlines?

A

Haemophilia:

  • Blood clotting disorder
  • Virtually all affected individuals are male, only a few affected females reported
  • A certain type of haemophilia has been observed in royal blood extending from Queen Victoria to the Russian imperial family and the Spanish Royal family
25
Q

What is a very common example of an x-linked disorder that is usually found in males?

A 
Colour Blindness:
- X-linked recessive trait
- Three receptors for light in eye:
> 2 genes encoding receptors for red and green light are X-linked (blue receptor gene is autosomal)
>  Rare but not impossible in females
26
Q

What is fragile x syndrome?

A
  • Many cases of mental retardation appear to follow a sex-linked pattern of inheritance
  • Often associated with a cytological anomaly - a constriction near the tip of the long arm of the X chromosome occurs which explains the name fragile x, because this tip is extremely fragile.
27
Q

What are the genotypes of male and female carriers of fragile x syndrome?

A
  • Affected females - heterozygous
  • Affected males - hemizygous
  • However, some carriers are unaffected
28
Q

What is an example of abnormalities in sex chromosome numbers?

A

Klinefelter Syndrome

  • 1:1000 births effected
  • 1 or more Y chromosomes and multiple X chromosomes
  • XXY or XXXY or XXYY
29
Q

What are the symptoms in males for Klinefelter Syndrome?

A
  • Reduced facial and pubic hair
  • Small testis
  • Taller than normal
  • Sterile
  • Normal intelligence
  • breast enlargement
30
Q

Are there any genes only on the Y chromosome?

A

Only a very few genes identified. This is unusual because these diseases would be very easy to see (ie. all progeny of an effected male would express the phenotype)

31
Q

What is the H-Y antigen?

A

Male-specific cell surface antigen

32
Q

What is TDF?

A

TDF (testis determining factor)=> critical for testicular differentiation and subsequent acquisition of male sexual characteristics

33
Q

What determines the sex of a human embryo?

A
  • Sex is determined by the dominant effect of the Y chromosome
  • Presence of Y Þ male
  • Absence of Y Þ female
34
Q

In sex determination, what are the steps for a female embryo to be produced?

A
  • Step 1: In the absence of a y chromosome no TDF is produced
  • Step 2: The lack of TDF allows the cortex of the embryonic gonads to develop into ovaries
  • Step 3: In the absence of testosterone, the embryo develops female characteristics
35
Q

In sex determination, what are the steps for a male embryo to be produced?

A
  • Step 1: The TDF is produced by the SRY gene on the Y chromosome
  • Step 2: TDF induces the medulla of the embryonic gonads to develop into testis
  • Step 3: The testis develop testosterone, a hormone that initiates development of male sexual characteristics.
36
Q

Where is the TDF gene found?

A

TDF is a gene on the Y chromosome in a region called SRY (sex-determining region-Y) which is just outside the pseudo-autosomal region

37
Q

How was SRY found

A
  • SRY was found by studying individuals whose sex was inconsistent with their chromosome constitution eg XX males and XY females.
38
Q

How do XX males and XY females still exhibit their gender traits even with the wrong chromosomes?

A
  • XX males carry a small piece of the Y chromosome in one of their X chromosomes
  • XY females have a small region of their Y chromosome deleted
39
Q

Give an example of an XY female

A

Caster Semenya

  • South African middle distance runner and world champion
  • Gender test revealed XY female
40
Q

What discovery about SRY is thought to suggest that SRY genes can bind to DNA?

A
  • SRY region is also present on Y chromosome of mouse and specifies male development in this species
  • Both human and mouse SRY genes encode a protein that can bind to DNA - suggesting that it may be a transcription factor which activates other genes necessary for testis development
41
Q

How does Androgen Insensitivity Syndrome (Testicular

Feminization) occur?

A

After the testes have formed, testosterone is secreted and initiates the development of male sexual characteristics.

  • Testosterone binds to the testosterone receptor present on the cell surface of target cells
  • Transmits a signal to the cell which influences differentiation, ie. It alters gene expression patterns such that male development ensues
  • If the signalling system fails then the individual develops as a female
42
Q

What happens to XY individuals with inactivating mutations in their testosterone receptor gene (Tfm)

A

They initially develop as males, testes are formed and testosterone is secreted, but because the testosterone signal cannot be transduced (it has no effect). These individuals develop female sexual characteristics however, do not develop ovaries.

43
Q

Why does Androgen Insensitivity Syndrome (Testicular

Feminization) occur

A
  • Due to a mutation in the X-linked, Tfm gene

- Mutated Tfm allele is transmitted from mothers to sons (who are phenotypically female) in typical X-linked pattern

44
Q

Draw and label a diagram for the Androgen insensitivity syndrome (testicular feminisation)

A

https://docs.google.com/document/d/1Nzo4FTzXCbwOZjpoc_J_4IF3gsOXPcoyC2BowELmx0U/edit?usp=sharing

45
Q

Give an example of the Androgen Insensitivity Syndrome in real life.

A

Maria Jose Matinez-Patiño

  • Spanish hurdler
  • Gender test revealed she had a Y chromosome
  • Complete androgen insensitivity syndrome, or CAIS
  • Declared ineligible for 1988 Olympic Games

Genetics & Evolutionary Biology (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions