Brainscape's Knowledge GenomeTM

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


See full index

Kaplan: Biochemistry Part II > Chapter I: Single Gene Disorders > Flashcards

Chapter I: Single Gene Disorders Flashcards

1
Q

What are homologous chromosomes?

A

when 2 chromosomes contain the same genes, but because one is paternal and one is maternal may contain different alleles

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

Pseudoautosomal regions

A

The name for regions on X and Y chromosomes that are homologous

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

Gene.

A

sequence of DNA that encodes a specific protein (or non translated RNA; i.e tRNA, rRNA, or snRNA)

(basic unit of inheritance)

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

Locus.

A

physical location of a gene on a chromosome

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

Alleles

A

variation (mutation) in the DNA sequence of a gene produces a new allele at that locus. (different forms of a gene)

Many genes have multiple alleles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Polymorphism

A

when specific site on a chromosome has multiple alleles in the population

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

Atlhough the term alleles is used most frequently with genes, can noncoding DNA also be said to have alleles of specific sequences?

A

yes

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

The β-globin gene has been mapped to what location on a chromosome?

A

11p15.5 a specific location on chromosome 11

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Is the β-globin gene polymorphic? Why?

A

yes because there have many mutations of it in the population and each mutation has created a new allele in the population

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

What is a genotype?

A

genetic makeup of organism

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

What are the types of single-gene mutations?

A

missense
nonsense
deletion
insertion
frameshift

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

Describe a missense mutation.

A

when there is a substitution of a single amino acid in the polypeptide chain

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

What is the missense mutation that leads to sickle cell?

A

caused by a missense mutation that produces a substitution

Valine replaces glutamic acid in the β-globin polypeptide

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

Describe nonsense mutations.

A

produce a stop codon resulting in a premature termination of translation and a truncated protein

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

Frameshift mutations?

A

When the inserted or deleted number of nucleotides is not a multiple of 3

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

In frame frameshift?

A

When the number of inserted or deleted bases is a multiple of 3

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

Can mutations occur in promoters and transcription factors?

A

yes

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

Loss of function mutations.

A

Mutations that cause a missing protein produce or cause decreased activity of the protein

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

What is recurrence risk?

A

the probability that the offspring of a couple will express a genetic disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Label the pedigree nomenclature diagram.

A

Label the image

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Meaning of proband.

A

the first affected individual to be identified in the family

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Tricks for identifying if a pedigree is showing an AD condition.

A
  • multiple generations of pedigree affected
  • skipped generation not typically seen
  • males and females affected equally
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

An example where two unaffected AD parents transmit disease causing allele.

A

if there was reduced penetrance

24
Q

Most common type of parent genotypes that cause AD conditions?

A

Aa (heterozygous affected) individual with an aa (homozygous normal)

25
Q

Recurrence rate for AD conditions.

A

50%

26
Q

Be able to identify this pedigree.

A

Autosomal Dominant

27
Q

What are important features that would help you distinguish AR inheritance

A
  • typically seen in only one generation of a pedigree
  • males and females affected equally
28
Q

Most common genotype of parents producing a child with an AR condition.

A

two heterozygous (carrier) parents

29
Q

Recurrence risk for offspring of the who have AR conditions?

A

25%

30
Q

List some major AD diseases.

A
  • familial hypercholesterolemia (LDL receptor deficiency)
  • Huntington disease
  • neurofibromatosis type 1
  • Marfann syndrome
  • acute intermittent porphyria
31
Q

Consanguinuity.

A

the mating of related individuals

32
Q

AR conditions.

A
  • sickle cell anemia
  • cystic fibrosis
  • phenylketonuria (PKU)
  • Tay-Sachs disease (hexominidase A deficiency)
33
Q

What is the inheritance pattern show in this pedigree?

A

Autosomal recessive

34
Q

What are some tricks to be able to ID X-linked recessive diseases?

A
  • skipped generations are commonly seen
  • male to male transmission not seen
35
Q

Identify the inheritance pattern shown in this pedigree

A

X linked recessive inheritance

36
Q

Name some X-linked recessive conditions.

A
  • Duchenne muscular dystrophy
  • Lesch Nyhan Syndrome (hypoxanthine-guanine phosphoribosyltransferase [HGPRT]
  • Glucose - 6- phosphate dehydrogenase deficiency
  • Hemophilia A and B
  • red-green color blindness
  • Menkes disease
  • Ornithine transcarbomylase (OTC) deficiency
  • SCID (IL-receptor y-chain deficiency)
37
Q

Describe how offspring born to an affected male with a homozygous normal female presents if the condition is X-linked recessive?

A

all of the daughters will be heterozyogous carriers: all of the sons homozygous normal

38
Q

What is the recurrence rate for a daughter with parents who have normal male with carrier female of an X linked recessive conditon?

A

recurrence rate for daughter is 0

39
Q

What is the recurrence rate for a male born to a normal male and female who is a carrier of an X linked recessive condition?

A

The recurrence rate for a son is 50%

40
Q

If the sex of a fetus born to a normal father and carrier mother is unknown, what is the recurrence rate in a fetus born to a normal male with a carrier female of an X-linked recessive condition?

A

Recurrence rate is multiplied by 1/2, the probability the the fetus is a male versus a female. Therefore if the sex is unknown, recurrence risk would be 25% overall

41
Q

Why are women said to be mosaics with respect to the active X chromosome?

A

because they have paternal X chromosome active in 50% of cells and maternal X active in 50% of cells

42
Q

X-chromsome inactivation is thought to be mediated by 1 mechinism or more than 1 mechinism?

A

more than 1

43
Q

What are some ways the body causes X-chromosome inactivation?

A
  1. A gene called XIST has been identified as the primary gene that causes X inactivation. XIST produces an RNA product tha coats the chromosome, helping produces its inactivation
  2. condensation into heterochromatin
  3. Methylation of gene regions on the X chromosome
44
Q

What exactly is genetic mosaiscism?

A

-the presence of 2 or more cell lines with different karyotypes in an individual.

-arises from mitotic nondisjunction

45
Q

How may a female at times express an X-linked recessive mutation? What is the term for this?

A

Because of random inactivation of the X chromosomes carrying normal allele have been inactivated

manifesting heterozygotes

46
Q

Why is the disease expression of a manifesting heterozygote typically milder?

A

because they have at least a small population of active X chromosomes carrying the normal allele

47
Q

Which arm of the Y chromosome contains a large block of heterochromatin?

A

the q arm

48
Q

Describe penetrance of males with Fragile X syndrome and symptoms?

A

Males: 100% penetrance
* intellectual disability
* large ears
* prominent jaw
* marcro-orchidism (usually postpubertal)

49
Q

Describe the penetrance in females with Fragile X syndrome and the symptoms.

A

Females: 60% penetrance
intellectual disability

50
Q

Is male to male transmission seen in X linked dominant conditions ?

A

no

51
Q

Some tips to determine if the inheritance pattern is X-linked dominant in a pedigee?

A

examine children of an affected male none of the sons will be affected but all of his daughters will have the disease (assuming complete penetrance)

52
Q

What is the inheritance pattern shown in this pedigree?

A

X-linked dominant inheritance

53
Q

Explain how and individuals sons and daughters are affected if the male is affected and copulates with a homozygous normal female? (X linked dominant condition)

A

non of the sons affected: Recurrence rate 0%

all the daughters affected recurrence rate 100%

54
Q

Recurrence rate if the sex of the fetus is unknown and there is an affected male with an X-linked dominant condition with a homozygous normal female?

A

then the recurrence rate is multiplied by 1/2 and overall recurrence rate is 50%

55
Q

Recurrence rate if a normal male mates with a heterozygous affected female with an X-linked dominant conditin?

A

50% of sons affected
50% of daughters affected

Kaplan: Biochemistry Part II (6 decks)

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