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NURS 1650 - Here We Go Again > Genetics > Flashcards

Genetics Flashcards

1
Q

Histones

A

Proteins that DNA wrap around

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2
Q

Chromatin

A

Repeating units of nucleosomes

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3
Q

Characteristics of euchromatin

A

Relaxed, loosely packed, genes are highly expressed

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4
Q

Characteristics of heterochromatin

A

Tightly packed together, genes are poorly expressed

Harder for enzymes to move past the tightly packed genes

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5
Q

During cell division, chromatin tightly condenses into _____

A

Chromosomes

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6
Q

What is a centromere?

A

The constriction point of a chromosomes that divides it into two sections

The location of the centromere gives the chromosome its characteristic shape and can be used to help describe the location of specific genes

Short arm –> p arm

Long arm –> q arm

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7
Q

What is a promoter? - Basic Structure of a Gene

A

Base-pair sequence that specifies where transcription begins

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8
Q

What is RNA coding sequence? - Basic Structure of a Gene

A

Base-pair sequence that includes coding information for the polypeptide chain (protein - although not yet in final form) specified by the gene

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9
Q

What is terminator? - Basic Structure of a Gene

A

Sequence that specifies the end of the mRNA transcript

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10
Q

What direction does nucleic acid synthesis occur in?

A

Synthesized in a 5’ to 3’ direction

DNA and RNA polymerases can only add nucleotides to the 3’ carbon on the previously incorporated base

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11
Q

What enzyme is responsible for the process of DNA replication?

A

DNA polymerase

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12
Q

Do all replication errors become mutations?

A

NO

Only when they are not corrected

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13
Q

What is the “end problem” in DNA replication?

A

The newly synthesized lagging strand has a gap of about 100 bases

This gap can start to eat into the chromosome, causing it to get shorter and shorter –> eventually lose functionality

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14
Q

What are telomeres? What do they do?

A

Complex of noncoding DNA & binding proteins at ends of linear chromosomes

Act like a cap on chromosomes

Maintain its structural integrity –> “solve” the end problem

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15
Q

What does a telomerase enzyme do? What kind of cells is it present in?

A

It maintains telomeric length by adding more tandem repeats to chromosomes

Present only germ cells, stem cells, and cancer cells

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16
Q

What is transcription?

A

Process of making an RNA copy of a gene sequence

In preparation for synthesizing the protein that gene codes for

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17
Q

3 Steps of Transcription

A

Initiation

Elongation

Termination

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18
Q

What does RNA polymerase do?

A

Initiates synthesis

lacks proofreading capabilities

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19
Q

What is an exon?

A

expressed sequence, translated protein

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20
Q

What is an intron?

A

intervening sequence removed during splicing, not found in mature mRNA

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21
Q

What is translation

A

Process by which mRNA is used to direct synthesis of a specific protein

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22
Q

tRNA Structure and Function

A

Carries amino acid to ribosome to lengthen the growing peptide chain

Recognition between mRNA codon and tRNA anticodon with complementary base pairing

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23
Q

What is the ribosomes job in translation?

A

Find starting place on mRNA

Line up tRNA on mRNA

Set correct reading frame for codon triplets

Catalyze peptide bonds that hold together amino acids

Releases newly synthesized protein chain when a stop codon is reached

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24
Q

What are Post-Translational Modifications? Why are they important?

A

Modifications of the polypeptide product of translation, after the translation process, is complete

NOT encoded in DNA, but are essential for the proper functioning of the protein

Increase protein functionality and diversity, regulate activity, localization, and interaction of proteins with other cellular molecules

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25
Q

Central Dogma

A

DNA

transcription

RNA

translation

Polypeptide

Folding or Post-Translational Modification

FINAL PROTEIN

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26
Q

What is a wild-type allele?

A

The allele that encodes the phenotype most common in a particular population

The “normal” allele

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27
Q

What is a mutant allele?

A

Any form of an allele other than the wild type

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28
Q

What is penetrance?

A

A measure of proportion of individuals in a population who carry a disease-causing allele AND express the disease population

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29
Q

What is complete penentrance?

A

ALL people with the allele display the disease phenotype

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30
Q

What is incomplete penetrance?

A

SOME people with the allele do not display the disease phenotype

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31
Q

What is expressivity?

A

The degree to which a genotype is expressed phenotypically in individuals

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32
Q

Not every mouse expresses purple tail pigment in their phenotype, despite having the requisite allele in their genotype.

What is this an example of?

A

Incomplete penetrance

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33
Q

Every mouse expresses purple tail pigment in their phenotype, but some tails are dark purple and some are light; pigment intensity varies

What is this an example of?

A

Variable expressivity

34
Q

Some mice have dark purple tails, some have light purple tails, and some have tails with no purple pigment

What is this an example of?

A

Both incomplete penetrance and variable expressivity

35
Q

Familial Adenomatous Polyposis (FAP) – if you inherit the disease-causing allele, you will get colon cancer, usually at an early age

What is this an example of?

A

Complete penetrance

36
Q

Hereditary Non-Polyposis Colorectal Cancer (HNPCC) – if you inherit the disease-causing allele, there is an 80% chance that you will get colon cancer, and can cause cancer in other organ systems

What is this an example of?

A

Incomplete penetrance with variable expresivity

37
Q

In people who have the allele coding for the mutation that causes achondroplasia, 100% of them will display the phenotype. This is known as _____

A

Complete penetrance

38
Q

In people who have the allele coding for a mutation that causes osteogenesis imperfect, some will have mild disease and some will have severe disease. These differences in disease severity are also known as __________

A

Variable expressivity

39
Q

What are the two common types of mutation at the single gene level?

A

Frameshift mutation

Point mutation

40
Q

What is a frameshift mutation?

A

The addition or removal of one or more bases changes the “reading frame”

Alters the primary structure of a protein

Deletion, insertion

41
Q

What is a point mutation?

A

Single base (and thus, base pair) substation

May cause affected codon to signify an abnormal amino acid

42
Q

What are the three subtypes of point mutations?

A

Missense –> wrong amino acid is made (ex. sickle cell anemia)

Nonsense –> a premature codon is inserted

Silent Mutation –> same amino acid is made (bc redundancy)

43
Q

Germ cell vs Somatic cell Mutations

A

Germline Mutation:
- Originates in germ cells
- Entire organism carries the mutation
- Half of the gametes carry the mutation

Somatic Mutation:
- Originates in body cells
- Affects a patch of area
- None of the gametes carry the mutation

44
Q

What is a monogenic disease?

A

One gene is mutated and is responsible for the disease

example: Sickle-cell Anemia (HBBgene)

Classification –> location: autosomal or sex chromosomes

45
Q

What are polygenic and multifactorial diseases?

A

More than one gene is mutated

Environmental factors may also play a role

example: T2DM

46
Q

Autosomal Dominant Diseases

A

Due to a mutation of a specific autosomal gene

1 mutant allele sufficient for disease phenotype to be expressed

47
Q

Autosomal Recessive Diseases

A

2 mutant alleles needed for the disease phenotype to be expressed

Unaffected may transmit to offspring

48
Q

Sex-Linked (X-linked) Disease

A

Mutation of sex chromosome (X)

Almost all are recessive

Males ALWAYS express // females when XX

49
Q

If G6PD were deficient in RBC, why would that be especially problematic? What is it about RBCs, in particular?

A

RBC have no nucleus

When undergoing large amounts of hemolysis, they cannot synthesize more

50
Q

What are Single-Nucleotide Polymorphisms (SNPs)?

A

DNA sequence variations where a single nucleotide is altered

51
Q

What are Genome-wide Association Studies (GWAS)?

A

seek to identify distribution of SNPs, across diff population, and associations of SNPs, rearrangements and copy number variants with various diseases

Can be used to predict an individual’s risk of developing a disorder

52
Q

When is/can a gene be expressed?

A

A gene is expressed when the protein for which it codes is created/synthesized

53
Q

What is gene regulation?

A

The process of turning genes on and off

54
Q

What is the role of miRNAs in gene expression?

A

Regulate proteins produced, prevent protein from being made

55
Q

What is epigenetics?

A

Modifications in gene expression without alteration of genetic structure

does NOT involve mutation, NO change in DNA sequence

56
Q

What is DNA methylation?

A

Most common modification in epigenetics

addition of methyl groups

low DNA methylation –> high level of expression

high DNA methylation –> low level of expression

57
Q

Polymerase Chain Reaction (PCR)

A

Takes short fragments (10,000 - 40,000 base pairs) and amplifies them to be studied

58
Q

Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)

A

Used for gene knockout, repression, or editing of a stretch of DNA within a gene

59
Q

DNA replication is:

A

Both continuous and discontinuous

60
Q

You would expect to find telomerase enzyme in which of the following cell types?

A

Liver cancer cells

Stem Cells

Sperm

61
Q

Which type of point mutation would result in a protein that is too short?

A

Nonsense

62
Q

Sickle Cell Disease is an autosomal _____________ disease and requires _________ copies of the mutated allele for the phenotype to be expressed

A

Sickle Cell Disease is an autosomal RECESSIVE disease and requires TWO copies of the mutated allele for the phenotype to be expressed

63
Q

In people who have the allele coding for a mutation that causes Marfan Syndrome, an autosomal dominant disease, some people have mild symptoms, such as being tall and thin with long, slender fingers. Others also have life-threatening dysfunction involving the cardiovascular system. These differences in disease severity are also known as ___________

A

Variable expressivity

64
Q

T/F
Offspring with XY chromosomes always express the disease if they inherit the mutated gene on the X chromosome

X-linked/Sex-linked Diseases

A

True

65
Q

T/F
All the offspring with XX chromosomes born to a father who has the disease will also have the disease.

X-linked/Sex-linked Diseases

A

False

We do not know the genetic status of the mother

66
Q

T/F
Offspring with XX chromosomes always express the disease if they inherit 1 copy of the mutated gene on the X chromosome.

X-linked/Sex-linked Diseases

A

False

Offspring with XX chromosomes would have to inherit 2 copies of the X chromosome with the mutated allele in order to express the disease. If they inherit 1 X chromosome with the mutation, their other X chromosome (without the mutation) can function normally

67
Q

T/F
Offspring with XY chromosomes, born to an affected father and a mother with no mutated gene on an X chromosome, will never inherit the disease.

X-linked/Sex-linked Diseases

A

True

68
Q

What is the clinical significance of familial hypercholesterolemia?

A

Atherosclerotic plaques would be expected to form in an affected person’s coronary arteries

An affected person will have very high blood levels of LDL cholesterol

Adolescents who are affected may have coronary artery calcification

69
Q

What is true of micro RNAs (miRNA)?

A

They provide a feedback system when a gene is expressed.

70
Q

CRISPR is a technique that can be used to:

A

Edit a gene

Silence a gene

71
Q

Missense Mutation Result

A

Wrong amino acid is made

ex. sickle cell anemia

72
Q

Nonsense Mutation Result

A

Premature stop codon inserted

Shorter protein

73
Q

Silent Mutation Result

A

Same amino acid is made

Bc redundancy

74
Q

Autosomal Dominant Example: Familial
Hypercholesterolemia (FH) –> autosomal dominant or recessive?

A

Autosomal dominant

75
Q

Patho of Familial Hypercholesterolemia (FH)

A

The gene that is mutated in Familial Hypercholesterolemia codes for a receptor in the liver that removes LDL cholesterol from the blood

Now cannot remove LDL-C from the bloodstream

Reduced clearance of LDL-C from circulation –> high levels of plasma LDL-C from birth

Increased atherosclerotic plaque formation w/ subsequent calcification

76
Q

Sickle Cell Disease is autosomal ____

A

recessive

77
Q

SCD Patho

A

the specific mutation found in sickle cell disease is a missense

causes a single amino acid substitution

causes the sickling shape

Results in ischemia, jaundice, anemia, destruction of the spleen, increased infections,

78
Q

G6PD Deficiency is a _____ disease

A

X-linked recessive disease

79
Q

G6PD Deficiency S/Sx

A

Jaundice, fatigue, tachycardia 2/2 acute hemolytic anemia

80
Q

Which disease appears to be protective against progression to severe malaria in about 2/3 of males?

A

G6PD Deficiency

NURS 1650 - Here We Go Again (20 decks)

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