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Genetics > Chapter 12: Chromosomal Basis of Inheritance > Flashcards

Chapter 12: Chromosomal Basis of Inheritance Flashcards

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Biology 101 flashcards
1
Q

Ploidy?

A

possible to get varying numbers of chromosomes

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2
Q

polyploids?

A

-extra sets ( triploid 3N, tetraploid 4N)

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3
Q

Aneuploids?

A

few more or few less than correct number of whole chromosomes present…aka one or more whole chromosomes of a normal set of chromosomes are missing or present in more than usual number of copies.

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4
Q

Examples of Aneuploids?(3)

A
  • Trisomy 23
  • Turner Syndrome (45, XO) 1/10000 females
  • Klinefelter syndrome (47,XXY) 1/1000 males
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5
Q

What are the two types of nondisjunction?

A
  • s the failure of chromosome pairs to separate properly during meiosis stage 1 or stage 2, specifically in the anaphase.
    1. primary nondisjunction : initial nondisjunction that the chromosome pairs do not separate producing gametes with the wrong number.
    2. secondary nondisjunction : occurs in an individual whose chromosomes were already wrong due to primary nondisjunction (they survived the initial one to go through a send)
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6
Q

Sex chromosomes?

A
  • chromosomes that are represented differently in different sexes.
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7
Q

Autosomes?

A
  • are chromosomes that are not represented differently in the two sexes
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8
Q

In humans and drosophila what represents male and what represents female?

A

male: XY

female : XX

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9
Q

Determination of sex:

Sex chromosomes are ____morphic. Female or maleness is determined by ____?

A
  • heteromorphic

- differences in the sex chromosomes

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10
Q

Determination of sex:

Ploidy : Hymenoptera…..males are?, females are?

A

males: haploid
females: diploid

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11
Q

Determination of sex:

- what kind of mechanisms that are not associated with sex chromosomes but contribute to the determination of sex?

A

allelic mechanisms

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12
Q

Determination of sex:

- in regards to genes what aids in the determination of sex?

A

a gene elsewhere in the genome

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13
Q

Determination of sex:

- environment and control of sex?

A
  • temperature (gekos)
  • temperature dependent sex determination
  • pivotal temp: in which there is a 1:1 sex ratio
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14
Q

Determination of sex:

- chromosomal mechanism? huh?(3 systems)

A
  • ZW system:
    L> ZW female; ZZ male
- XO system (single chromosome) 
L> XX female, XO male 
-Compound chromosomes 
L> various combinations of X and Y 
L>some beetles
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15
Q

XY system:

  • females have ___ pairs of homomorphic, homologs chromosomes and are therefore called?
  • males have ___ pairs of homomorphic, homologous chromosomes and one pair of ___ chromosomes and are therefore called?
A
  • 23; homogametic
  • 22, heteromorphic
  • L>heterogametic
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16
Q

Maleness is not just a ?

A

Y

17
Q

XY system: think maleness

  • Is the Y chromosome an absolute determination of maleness?
  • XO genotype should always produce a female; XO in humans? XO in drosophila ?
A
  • no
  • but it doesn’t
  • female
  • male
18
Q

What does the Y chromosome in drosophila represent?

A
  • it just means fertility of a male…the ratio of X chromosomes to autosomes is what determines sex.
  • XXY = female
    L> *2X= autosomes
19
Q

X-linked inheritance??

A
  • can be recessive or dominant

L> resulting from the presence of a mutant allele carried by the x-chromsome

20
Q

Reciprocal crosses reveal what about X-linked inheritance ?

A
  • different transmission patterns, different ratios are seen for the two seeds of offspring
21
Q

Disjunction of X chromosomes?
- If you cross a white eyed female with a red eyed male? (regular disjunction)
W/W (white eyed female) x W+/Y (red eyed male)

A

w+ Y
| WW+ WY
W| WW+ WY (1/2 red eyed females, 1/2 white eyed males)
regular disjunction

22
Q

Nondisjunction of X chromosomes:

- Rarely, if you cross a white eyed female with a red eyed male what will you get?

A
  • W/W x W+/Y
  • you will get white eyed females and red eyed males
    due to nondisjunction.. XX eggs and OOeggs
    white eyed female: WWO … red eyed male: W+Y (parents)
             W+             Y
 WW     WWW+      WWY 
O         W+O           OY 
F1:
dead: WWW+, OY  (all autosomal no sex chromosomes) 
W+O= red eyed female but not fertile 
WWY= white eyed exceptional female and is fertile 
 Normal disjunction:
WWY    x     W+Y 
           W +             Y
W     WW+          WY
WY    WW+Y       WYY 
2nd nondisjunction:

WWY x W+Y

           W+       Y WW      WWW+     WWY

Y W+Y YY
dead: YY, W+WW
W+Y= red eyed male
WWY= white eyed female exception

23
Q

X-linked Recessive Inheritance?

  • genotype of females needed to express?
  • passing on from an affected mum?
  • passing on from an affected dad?
A
  • females must be homozygous to express the trait
  • all sons of an affected mother exhibit the trait
  • carrier females pass affected allele onto 1/2 sons and 1/2 daughters
  • affected males transmit the mutant gene to all daughters.
24
Q

X-linked Dominant inheritance?

  • affect father and passing on?
  • passing on from a heterozygous mother?
  • min needed to express trait in females?
A
  • if affected father, all daughters and none of the sons will be affected
  • heterozygous mothers transmit the trait to 1/2 sons and 1/2 daughters
  • heterozygous females express the trait
25
Q

Y-linked inheritance?
L>definition, another name?
- an affect male and passing on?

A
  • a trait resulting from a mutant gene that is carried on the Y chromosome but has no counter part on the x-chromosme …this is also called holandric trait (wholly male)
  • all sons will get it but none of the daughters will
26
Q

Autosomal Recessive?

  • the trait often is present in every generation or does it skip?
  • ratio of affected males and females?
  • If bot parents are affected, the progeny?
  • most affected individuals have both parents affected or one is and the other is not affected or both are unaffected?
A
  • skips a generation
  • equal number of males and females re affected
  • all progeny will be affected
  • have unaffected parents
27
Q

Autosomal Dominance?

  • the trait often is present in every generation or does it skip?
  • ratio of affected males and females?
  • Affected person if heterozygous mates with an unaffected person, what is seen in the progeny?
A
  • trait does not skip
  • equal number of males and females affected
  • 50% of offspring should be affected
28
Q

X-chromosme inactivation?

  • a double dosage of X chromosome gene products is lethal/nonlethal?
  • What occurs if one of 2 X’s randomly inactivates?
A
  • lethal
  • all progeny cells have same inactivated X, the product of that x chromosome genes will show in phenotype that cell…aka product of the non-inactivated X chromosome genes will show in the phenotype of the cell.
  • bar body in us*
29
Q 
X-chromosme inactivation? 
- calico cat fur colour 
- OoB- 
O=?
B=?
Dominance?
A

O= sex linked
B= autosomal
O is dominant to B, if not inactivated

Genetics (14 decks)

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