Brainscape's Knowledge GenomeTM

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


See full index

POM 1a: Genetics (6) > 5.1: Modes Of Inheritance > Flashcards

5.1: Modes Of Inheritance Flashcards

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

What does dominance refer to?

A

Phenotype

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

How is a characteristic dominant?

A
  • if it manifests in a heterozygote (2 alleles in a locus)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Why are brown eyes dominant?

A

-OCA-2 gene responsible
-Active OCA-2 = BROWN EYES
-Inactive OCA-2 = BLUE EYES

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

What are the 5 characteristics of dominant autosomal disorders?

A
  1. Single gene disease
  2. Multiple generations affected
  3. Affected person normally has an affected parent
  4. 1/2 chance of offspring having disease
  5. Males and females are equally affected
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens if you are homozygous for dominant autosomal disease (RR)?

A

Usually lethal disease

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

What is the pedigree pattern for dominant autosomal disorders?

A

Vertical pedigree pattern

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

What are the 3 ways that diseases can be dominant?

A
  1. Gain of function
  2. Dominant negative effect
  3. Insufficient
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is Gain-of-Function?

A

Genes makes a protein with a new function
-e.g/ constitutively active; protein aggregation (toxic)

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

What is the dominant negative effect?

A

Mutated form of gene interferes with the activity of proteins
-e.g/ binding of dimers/multimers which reduces activity

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

What is Insufficient?

A

Mutant in one gene results in 1/2 amount of protein made that is not enough for function
Rare - usually affects collagen

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

What is the mutation that causes Huntington’s disease?

A

Results from expansion CAG (glutamine) repeat - produces protein huntingtin

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

What is the result of the mutation that causes Huntington’s disease?

A

Abnormal intracellular Huntington protein aggregate —> gains pathological function —> toxic to neurones = cell death

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

What mutations causes Brittle Bone disease?

A
  • Type I = insufficient quantities of collagen
  • Type 2,3,4 = abnormal protein with altered structure that interferes with the function of the normal protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the result of the mutation that causes Brittle Bone disease?

A

Wearing of connective tissue - especially bone

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

What is a carrier of a autosomal recessive disorder?

A

-They have lost a single copy of gene
- BUT normal one is sufficient to maintain normal function

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

What are autosomal recessive disorders?

A
  • 2 copes of abnormal gene must be present in order for disease/trait to be develop
  • Tend to be ‘loss of function’ mutations (e.g/deletions)
17
Q

What are the 4 characteristics of autosomal recessive disorders?

A
  1. Parents and children of affected people are NORMALLY unaffected
  2. One of more siblings affected
  3. Offspring has 1/4 chance of being affected (compared to affected sibling)
  4. Males and females equally affected
18
Q

What is the pedigree pattern for autosomal recessive disorders?

A

Horizontal pedigree pattern

19
Q

What can increase the chance of being affected by a recessive disorder?

A

Consanguineous marriage (cousin marriages)

20
Q

What are the characteristics of cystic fibrosis?

A
  • failure to thrive
  • defective chloride ion channel
  • results in impaired airway defence
    -prone to respiratory infections
    -digestive issues
21
Q

What mutation causes cystic fibrosis?

A

Various mutation in a gene encoding chloride ion channel (CFTR gene on chromosome 7)

22
Q

What is the result of the mutation that causes Cystic fibrosis?

A
  • Defective chloride ion channel - Cl does not move out of cell = mucus builds up outside
  • Loss of function; work less well; degraded faster; present inadequate amounts
  • recessive as gene for single channel is sufficient to maintain activity
23
Q

What are the sex chromosomes?

A

-consists of X and Y chromosome
- determines the sex
- X = 1000-1300 genes (850 protein coding)
- Y = 150 genes (50-70 protein coding)

24
Q

Who do the X-linked disorders (recessive) affect?

A

Mainly males (effectively dominant)
- females can be carriers and affected males are linked through females
- affected boys may have affected uncles
- homozygous females have the disorder
-parents and children of affected NORMALLY unaffected

25
Q

What happens if the mother is the carrier of an X-linked recessive disorder?

A
  • Brothers of affected son = 1/2 chance of having disorder
  • Sisters = 1/2 chance of being CARRIER
26
Q

What happens if the father has an X-linked recessive disorder?

A

-All daughters will be CARRIERS
-All sons will be healthy (inherits Y from dad)

27
Q

What are the 5 characteristics of X-linked DOMINANT disorders?

A
  1. Similar to autosomal dominant pattern
  2. All daughters of affected father AFFECTED; no sons affected
  3. Condition often MILDER and VARIABLE in females than males - due to X chromosome inactivation
  4. Some disease only present in females - as not viable in males
  5. Gain of function mutation
28
Q

Example of Dominant X-Linked disorder: Hypophosphatemia

A

Low levels of phosphate in blood
1. PHEX gene mutation
2. Overproduction of FG21
3. FG21 inhibits kidney phosphate resorption
4. Kidney cannot retain phosphate
5. Results in Vitamin D-resistance rickets

29
Q

What are the 3 characteristics of Y-linked disorders?

A
  1. Affects only Males
  2. Affects all sons of affected father
  3. Vertical pedigree pattern
30
Q

Features of Mitochondria?

A
  1. Have their own DNA
  2. Majority mitochondrial proteins encoded by nuclear genes
  3. Mutations in these gene cause most mitochondrial disease
  4. Some diseases are caused by mutations in mitochondrial DNA
31
Q

What are the 5 characteristics of Mitochondrial inherited disorders?

A
  1. Disease caused by mutations in mitochondrial DNA
  2. Maternally inherited as ALL mitochondria is inherited from mother
  3. All children of affected women may be affected
  4. Children of affected men are NEVER affected
  5. Mitochondrial conditions are typically extremely variable even WITHIN a family
32
Q

What is the pedigree pattern for mitochondrial inherited disorders?

A

Vertical pedigree pattern

33
Q

Why is there mitochondrial disease variability?

A

-mitochondria have multiple copies genome; some mutant & sone normal
-only express disease effects if mutant is ABOVE a thread hold
-reproduce by binary fission (similar to bacteria) —> can gain/lose mutated genes in this process = VARIABILITY

34
Q

How is mitochondrial disease variability inherited?

A
  1. Many mitochondria in each cell
  2. Random segregation
  3. Symptoms develop once threshold reached - numbers of cells with mutant mitochondria can change with time
  4. Develop with age due to accumulation of mutant mitochondria

POM 1a: Genetics (6) (1 decks)

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