Brainscape's Knowledge GenomeTM

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


See full index

Pathology Summer 2020 > Genetics > Flashcards

Genetics Flashcards

1
Q

____ are the foundation for all cellular structure and function

A

Proteins

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

How many genes in the human genome

A

50,000

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

What percent of DNA is used to make proteins?

A

10%

8% is regulatory and 2% is the actual code for the protein

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

Exons

A

Portion of gene that is transported out of the nucleus and translated into a protein

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

Different types of introns

A

Portion of gene removed from RNA transcript before translation.

  • Non coding part
  • No translation to protein (RNA splicing)
  • Regulation of gene expression
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What factors may effect transcription?

A

External factors such as toxins and medicine
Internal factors such as cytokines

Both can elicit or inhibit RNA transcription.

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

Epigenetics and examples

A

Extra-DNA modifications to the genome. Influences phenotype. Does not change the DNA sequence and is not encoded in the DNA sequence.

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

Examples of epigenetics that can affect genome

A

Chemical compounds. Methylation silences.
Can be inherited
Can be acquired by external factors such as diet, pollutants.

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

How does methylation affect the genome

A

It silences the gene. No transcription.

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

Autosome vs allosome

A

Autosome: Homologous pairs (1-22)
Allosome: Sex chromosomes (23)

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

How is DNA wound?

A

Double helix organized by histones into nucleosomes. Condensed into chromatin that make up chromatids.

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

Locus

A

Location of a gene/marker on a chromosome.

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

Diploid cells have ___ loci per gene

A
  1. One per chromosome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Allele:

A

Gene variant at a particular locus.

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

Homozygous vs heterozygous

A

Homo: Both alleles are the same on each gene locus.
Hetero: different alleles. Some genes have few alleles, other have thousands.

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

Non-mendelian genetics

A

Penetrance (complete and incomplete) and expressivity.

Both can be affected by lifestyle/environmental factors.

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

Penetrance

A

Likelihood of manifesting a particular phenotype given the same genotype.

Complete- everyone with the same genotype manifests the same phenotype.

Incomplete (variable)- Everyone has the same genotype, but some do not manifest the same phenotypes.

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

Expressivity

A

Degree to which the phenotype is expressed.

Variable expressivity: Degree of phenotype expression varies between individuals with the same genotype.

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

Mendelian Inheritance (6 patterns of inheritance are observed)

A 
Co-dominant 
Autosomal dominant 
Autosomal recessive 
X-linked dominant 
X- linked recessive 
Mitochondrial
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Autosomal dominant disorder passing down rate

A

Each child has a 50% chance of inheriting the disorder.

Affects male and females in each generation

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

Ocular examples of autosomal dominant disorders

A

Retinitis Pigmentosa. Progressive vision loss.

Dominant Optic Atrophy. Progressive vision loss.

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

Retinoblastoma

A

Rb1 gene mutation.
90% of patients who have the gene will develop the condition.

Considered autosomal dominant with reduced penetrance.

Usually unilateral.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Autosomal recessive disorder passing down rate.

A

Each child has a 25% chance of being affected.
Both parents must be at least heterozygous (carriers) to transmit the disorder.
Appears equally in male and female children of unaffected parents.

24
Q

Autosomal recessive disorder almost always associated with the _____ of the affected gene.

A

Loss of function.

25
Q

Ocular examples of autosomal recessive

A

Retinitis pigmentosa

Congenital stationary night blindness

26
Q

Sickle Cell disease

What kind of mutation is it?

A 
Point mutation on chromosome 11
Missense mutation (1 change in BP)
27
Q

What happens in patients that have sickle cell anemia?

A

Lowered levels of oxygen cause crisis.

Cells sickle and become sticky, blocking blood flow and can cause clot formation.

28
Q

__% of african americans have sickle cell traits.

A

9

1 in 600 AA have sickle cell anemia.

29
Q

Ocular manifestations of

A

Ischemia causes retinopathy
“sea fan” neovascularization
Vitreous hemorrhages
Retinal detachements

30
Q

Codominant inheritance

A

One gene has more than one allele that can be expressed.
Phenotype is influenced by both inherited alleles.
Ex: ABO locus

31
Q

X-linked dominant disorders inheritance

A

Affected males pass the disorder to all daughters, but no sons.

Affected heterozygous female pass condition down to half their sons and daughters.

32
Q

Ocular example of x linked dominant disorder

A

Ocular albinism

33
Q

Fragile X syndrome

A 
Tri-nucleotide repeat disorder 
Variable penetrance 
Variable expression 
-males express more than females 
-Ocular manifestations (strabismus and refractive errors)
34
Q

X-linked recessive disorders affect males or females more?

A

Males. Asymptomatic female carriers transmit the disorder to 50% of their male offspring.

Ex: red-green colorblindness. Retinitis pigmentosa.

35
Q

X linked ocular disorders

A

Red-green color blindness.
Congenital stationary night blindness.
Retinitis pigmentosa
Choroideremia- nyctalopia

36
Q

Mitochondrial inheritance disorders

A

Only passed down by mothers.
Disorders appear in every generation of a family
Males = females, but expressivity can change between males and females. Usually affects males more.

Ex: lebers Hereditary optic neuropathy (Apoptosis of RGC)

37
Q

Chromosomal disorders. When do they occur?

A

Reflect events that occur at the time of meiosis as gametes are being formed.

Ex: Nondisjunction or breakage of chromosome with loss or translocation of genetic material (translocation/deletion)

38
Q

Two types of nondisjunction

A

Results in unequal separation of chromosomes during meiosis (chromosomal disorders) or mitosis (mosaicism). Manifestations will be different for each.

39
Q

Results of nondisjunction

A

Results in 22 or 24 chromosomes in the egg or sperm.

Turner syndrome: 22 + 23 = 45 chr
Down Syndrome: 24 + 23 = 47 chr

40
Q

Karyotype

A

Family photograph of chromosomes

41
Q

Ocular manifestations of down syndrome

A

Epicanthic folds
Brushfield spots (circle around iris)
Refractive error
Early onset cataracts

42
Q

Klinefelter’s syndrome

A

Nondisjunction of sex chromosome (23)

Person ends up with 47 chromosomes (XXY)

43
Q

How to diagnose Klinefelters syndrome

A

One barr body (condensation of one of the X chromosomes)

44
Q

Signs and symptoms of Klinefelters

A

XXY.
Phenotypical male.
Hypogonadism. Female secondary sex characteristics at puberty.

45
Q

Turner Syndrome

A

Non-disjunction of 23

45, X karyotype.

46
Q

Most common monosomy

A

Turner syndrome. 45, X

47
Q

Signs and symptoms of X

A

Short stature, shield chest, webbed neck, reproductive sterile. Heart and kidney defects.

48
Q

Ocular manifestations of Turners syndrome

A

45, X

Many binocular vision problems.

49
Q

Chromosomal translocation

A

Transfer of chromosome parts between non-homologous chromosomes.

50
Q

Robertson translocation

A

Unbalanced chromosomal translocation. Unequal parts of chromosomes are exchanged.

Additional cause of down syndrome.

51
Q

Example of chromosomal deletion

A

Cri du chat syndrome. Loss of the short arm of Chromosome 5.

52
Q

Two chromosomal deletions that affect the eye

A

WAGR (chr 11- aniridia)

Retinoblastoma (chr 13 deletion) Due to loss of tumor suppressor gene.

53
Q

Ocular manifestations of Cri-du-chat syndrome

A

Hypertelorism- broadly spaced eyes
Epicanthal folds
Down slanting palpebral fissures
Strabismus

54
Q

Hypertelorism

A

Broadly spaced eyes. Seen in Cri du chat syndrome.

55
Q

Mosaicism

A

Could be due to non-disjunction or point mutations during mitosis. After fertilization, but early in development.

Ex; heterochromia.

56
Q

Polygenic/multigenic disordres

A

Disease incidence is affected by multiple genes in addition to lifestyle and environmental factors.

Pathology Summer 2020 (19 decks)

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