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MOD S1 > Lecture 3 E1 -Genetics pt 1 > Flashcards

Lecture 3 E1 -Genetics pt 1 Flashcards

1
Q

how is genetic material stored

A

as DNA, a stable macromolecule

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2
Q

what does DNA do

A

what to do, when , why, and how

Determines disease susceptibility
-many diseases have a genetic component
-most are polygenic, but there are some that are single gene disorders

Determines how we react to drugs

Determines our appearance, like how tall we CAN be

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3
Q

how long can DNA survive?

A

Through the main stages of replications, cell divisions, renewal and growth

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4
Q

what is a genome, what are the two types

A

All genes in the body

Nuclear and cytoplasmic

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5
Q

describe the structure of DNA and RNA

A

DNA and RNA are molecular chains that have a repeating modular structure consisting of two deoxyribose for DNA and ribose for RNA bound to one of the four nucleic acids

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6
Q

what is involved in the actual synthesis of cellular proteins

A

RNA

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7
Q

four bases

A

adenine
guanine
thymine
cytosine

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8
Q

which acids are purines, which are pyrimidines

A

adenine and guanine are purines (teo nitrogenous rings)

thymine and cytosine are pyrimidines (one nitrogen ring)

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9
Q

what is uracil

A

In RNA, lacks methyl group on its ring, replaces thymine

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10
Q

what is mitochondrial DNA

A

the cytoplasmic genome

small portion of DNA of a cell resides in mitochondria

double stranded, closed circle, containing 37 genes for DNA translation and oxidative metabolism

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11
Q

what is mitochondrial DNA used for

A

translation and oxidative metabolism

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12
Q

where is mitochondrial DNA inherited from

A

usually from the mother only

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13
Q

how does dna exist at resting state

A

Two strands of DNA running anti-parallel to each other that are wound in a double helical structure
double helix

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14
Q

how are DNA strands held together

A

Specific hydrogen bonds that form between purines and pyrimidines

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15
Q

what do the purine and pyrimidine specificity cause

A

DNA strands to be complementary to each other

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16
Q

what does double stranded DNA structure allow

A

replicating precisely by separation of two strands followed by synthesis of two new complementary strands

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17
Q

what is a gene

A

piece of DNA that encodes a product

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18
Q

what are genes made up of

A

pieces of DNA spelling out the genetic code for making a specific protein

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19
Q

how many gene pairs are there

A

several hundred to 1 million

vary in size

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20
Q

what makes up the alphabet of the genetic code

A

nitrogenous bases make up alphabet

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21
Q

what makes a codon and how is it decoded

A

sequence of 3 bases makes a codon which is a nucleotide triplet necessary for protein synthesis

the specific amino acid sequence can be decoded by reading groups of three consecutive bases

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22
Q

what is the template strand

A

what is transcribed into RNA (into codons)

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23
Q

how many codons are there

A

64,

each is a 3 base triplet and there are 4 possible bases for each position

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24
Q

what is functional redundancy or degeneracy

A

meaning that the amino acid can be specified by more than one codon

(most aminos acids are)

ex; AUG serves the dual functions of signaling the start of translation and encoding methionine

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25
Q

what are synonyms of genetic code

A

codons differing only at third base position will typically code for the same amino acid or amino acids with similar chemical properties

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26
Q

what 3 codons do not signal amino acids

A

UGA, UAA, UAG
stop or termination codes

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27
Q

how is DNA genetic message delivered to the cytoplasm of a cell

A

by RNA

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28
Q

How are genes determine?

A

Hey single alleles meaning monogenic or many alleles polygenic

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29
Q

what do any diseases result from?

A

Damage to genes are chromosomes.
The damage can be spontaneous or an environmental insult or an inheritable defect

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30
Q

what is mutation considered

A

Mutation is not associated with a disease phenotype. It is considered a variant or polymorphism.

It typically accounts for differences in gene expression in proteins function that still allow functioning within normal range, contributing to human variability

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31
Q

What are mutations a result of

A

result of errors in the DNA duplication and become a permanent structural alterations in DNA

Typically refers to changes in the genome that cause sufficient change in expression or function, so that a path of physiological state results

effects of mutations can be variable

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32
Q

How are mutations often resolved?

A

By DNA repair mechanisms, but these mechanisms can fail, allowing the damage genetic material to be passed on

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33
Q

what is the transmission of genetic mutation affected by

A

Expressivity of the mutation, or the way the genotype is expressed in the phenotype

Range from mild to severe

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34
Q

what is transmission genetics

A

Repetition and division of DNA mutations through generations

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35
Q

what is penetrance

A

The ability of a gene to expressive mutation, which can influence the effects of genetic mutations

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36
Q

what mutations can be transferred generationally

A

Somatic (generic cells) and germline mutations

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37
Q

what is the most common form of DNA variation?

A

Single base substitution

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38
Q

What is the single substitution and how is it characterized?

A

Replacement of one base for another base in the DNA sequence

A single nucleotide polymorphism

well characterized- mendelian disorders - CF

don’t usually cause problems but if it does it is named

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39
Q

what is a nonsense mutation?

A

Substitution that changes a codon for an amino acid to stop codon, leading to the premature termination of translation of the mRNA transcribed in a truncated protein

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40
Q

what is a missense sense mutation

A

A substitution that changes the codon for one amino acid to the codon for another amino acid. The size of the mRNA and proteins are not changed but the composition, and possibly the function of a protein does change.

*switch it out mutation

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41
Q

what is a splice site mutation

A

Substitution in one of the base pairs inside or flanking the intron exon boundaries that alters normal pre-mRNA splicing.
Such mutations can result in an intron retention(partial or complete) or exon skipping.

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42
Q

what is a silent mutation?

A

A change in one base that results in no change in the amino acid sequence of the proteins, due to the redundancy of the genetic code

(There is more than one codon for most amino acids)

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43
Q

what is a regulatory polymorphism?

A

a substitution that alters binding affinities of transcription related proteins, such as transcription factors, enhancers, silencers, or insulators
may show up in wrong spot

Such changes result in altered rates of transcription

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44
Q

what is RNA?

A

Molecule that is responsible for the assembly of our proteins

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45
Q

RNA versus DNA

A

Is single-stranded, the sugar backbone of RNA is ribose, the pyrimidine base uracil for RNA replaces thymine for DNA

46
Q

what is the messenger RNA

A

Provides a template for proteins synthesis, depending on the codon sequence of the DNA strand

Carries instructions from the DNA molecule into the cytoplasm

Formed by the process of transcription

47
Q

what is ribosomal RNA

A

Ribosome is the structure of the cytoplasm where proteins synthesis takes place

Makes up a ribosomes, which are transported from the nucleus to the cytoplasm, and begin proteins synthesis, or translation of the genetic code

48
Q

what is transfer RNA

A

A clover shaped molecule that functions to deliver the activated form of amino acid to the proteins that is being synthesized in the ribosomes

Each tRNA recognizes and binds a specific amino acid, which it transfers to ribosomes

*brings amino acids into complex to make new proteins

49
Q

What is transcription?

A

Involves the copying of the genetic code from DNA to a complementary strand of mRNA

50
Q

What is a template strand

A

RNA polymers reads from this to make a copy of the DNA to RNA

51
Q

Where does transcription happen?

A

nucleus

52
Q

what is transcription initiated by?

A

Enzyme called RNA polymerase, which binds to a specific promoter site on the DNA

53
Q

when does transcription stop?

A

Transcription will continue to copy the strand of DNA until it reaches a terminator

now it can be processed (adding cap, tail, splicing)

54
Q

What happens after a terminator is reached in transcription

A

RNA polymerase enzyme will leave the gene and release the premature RNA strand for further processing

55
Q

what are the beginning and end of a gene called

A

promotor, terminator

56
Q

post transcription modification of mRNA

A

RNA transcription is a continuous process, yet the DNA sequence that codes for proteins (exons) is often interrupted by interviewing, non-coding sequences(introns)

These intron segments must be removed or spliced from the RNA prior to translation

57
Q

What does the splicing process lead to?

A

Several different proteins from one gene as you can mix and match exons together

58
Q

what does differential splicing of coding exons result in?

A

Differences in the ultimate proteins structure

59
Q

what happens once mRNA has been processed

A

Diffuses through the nucleus pores into the cytoplasm, where it will travel to the ribosomes and control proteins synthesis

60
Q

Why do we keep introns

A

Because they allow the synthesis of more than one protein from the same gene

61
Q

what is mature mRNA made of

A

only exons

62
Q

example of alternative splicing

A

leaving out one exon would have the same sequence but would make a different protein

63
Q

what is translation?

A

The process of taking the instructions from the mRNA, and transferring them to the rRNA of ribosomes located in the cytoplasm

mRNA binds to ribosome and is transcribed and instructions sent to tRNA to transfer the correct amino acid to the growing peptide chain

Newly synthesize proteins and folds into its functional form and is sent to its final position in the cell
64
Q

What are chromosomes

A

Chromosomes are composed of double strand of DNA containing sections of genes

65
Q

what happens to chromosomes during cell division

A

Chromosomes reproduce their physical and chemical structures to pass on genetic information in one of two processes
mitosis or meiosis

66
Q

What is mitosis?

A

Chromosomes in the nucleus of somatic cells, go through a series of phases, resulted in the creation of daughter cells with the same chromosome number, and genetic make up as the original cell

67
Q

what is meiosis

A

Process where one germ cell divides into for cells, each with half set of chromosomes

68
Q

What is ploidy?

A

The number of sets of chromosomes you have

69
Q

somatic cells chromosomes

A

Somatic cells contain chromosome pairs
Each somatic cell contains two sets of 23 chromosomes, diploid number of chromosomes
44 chromosomes are autosomes, and two are sex chromosome (X,Y)

70
Q

what are gametes

A

Ova and sperm
contain only one set of chromosomes

haploid number of chromosomes

71
Q

what results in the diploid number of chromosomes

A

combination of ova and sperm genetic material at the time of conception results in a cell with the diploid number of chromosomes

72
Q

what are somatic cells

A

non reproductive

23 pairs of diploid chromosomes

formed during mitosis

73
Q

what are gametes

A

reproductive cells

contain 23 single stranded chromosomes (haploid)

formed during meiosis

74
Q

describe mitosis

A

-process in which somatic cells replicate and divide to produce identical daughter cells each with 23 pairs of chromosomes

75
Q

what are daughter cells

A

same chromosome number and genetic makeuo as original cell

76
Q

what are the four phases of mitosis

A

prophase, metaphase, anaphase, telophase

77
Q

what is meiosis

A

process in which gametes (reproductive cells) are formed

each cell contains single set of 23 chromosomes

78
Q

what is spermatogenesis

A

production of viable spermatids

79
Q

what is oogenesis

A

production of one viable ovum and three polar bodies (of 4 produced, 3 degenerate along the way and only one turns into an egg)

80
Q

what is dijunction

A

when chromosomes separate during mitosis and meiosis

81
Q

what is recombination

A

process of chromosomes coming back together in mitosis and meiosis

82
Q

what is nondisjunction

A

when chromosomes(sister chromatids) fail to separate (when they should during disjunction)
- one cell gets an extra and one gets none

83
Q

aneuploidy

A
  • results in unequal number of chromosomes between cells
    -not the whole set but 1-2 chromosomes may get extra
  • ## common in meiosis in people
84
Q

is aneuploidy more common in sperm or eggs

A

eggs

85
Q

polyploidy

A

not common in humans, more common in nature
results form chromatids not pulling apart, you get multiple sets)

86
Q

how many newborns does aneuploidy affect

A

1:300

87
Q

what increases risk of aneuploidy

A

maternal aging
5% at age 30
10% age 35
15% age 39
35% age 42

88
Q

what age group is at risk for aneuploidy

A

young teens (less than 16 years)

89
Q

how is aneuploidy written

A

n+- # of extra chromosomes you have (or dont have)

90
Q

-omy

A

aneuploidy

91
Q

-ploidy

A

polyploid (triploid)

92
Q

monosomy

A

(one-aneuploidy)
presence of only one member of a chromosome repair (missing one of a pair)

occurs when nondisjunction results in cells with one copy of a chromosome instead of two

usually incompatible with life

exception is turner syndrome (chrom 45, missing X)

93
Q

what is turner syndrome

A

absence of all or part of X chromosome (monosomy)

most common genetic disorder in women

short stature, wide set nipples, webbed neck

no secondary sex characteristics

normla intelligence

often diagnosed with short stature or failure to enter puberty

94
Q

what is polysomy

A

presence of more than two chromosomes to a set

95
Q

when does polysomy occur

A

when a germ cell containing more than two chromosomes is involved in conception

96
Q

what is trisomy

A

presence of three copies of a chromosome per cell

if large chromosome is affected, excess of genetic material is incompatible with life

97
Q

trisomy 21

A

most common
down syndrome

98
Q

trisomy 13 and trisomy 18

A

edward syndrome
more severe and result in early death in most cases

99
Q

can trisomy of sex chromosomes occur

A

yes, and it is more compatible with life
47, XXY kleinfelter syndrome
47, XXX triple X syndrome

100
Q

down syndrome

A

first described 1866
most common chromosomal disorder
increased risk with advanced maternal age
95% due to nondisjunction during meiosis- trisomy 21

characteristics-
flattened nasal bridge, epicanthal folds, protruding tongue, simian crease

prenatal screening- AFP, hCG, PAPP-A, nuchal translucency, *karyotype most accurate

101
Q

kleinfelter syndrome

A

extra X chromosme (polysomy)
nondisjunction during meiosis, usually maternal
1:1000 males, many unaware
enlarged breasts, sparse body hair, small testes, high voice
infertility, osteoperosis later
treated with androgens
(lower IQ than sibs, tall stature, poor muscle tone)

102
Q

mosaicism

A

presence of two or more genetically different sets of cells
result from early errors in mitosis
expressed in a percentage based on blood analysis
if mosaicism made up of normal and abnormal karyotype, deformities less severe

(can affect pigmentation, some cancers)
mitochondria mutation (cells can end up with functioning or mutated mitochondria)
random X inactivation ( parts of body may express dads or moms X chromosome)

103
Q

what is linkage/recombination

A

typically alleles of different genes sort independently during meiosis but

genetic linkage- genes in close proximity sort together

crossing over/homologous recombination- when genes of same chromosome sort independently

104
Q

structural abnormalities of mutations

A

occurs due to breakage and subsequent rearrangement or deletion

multiple patterns (deletion, translocation, inversion, insertion, duplication)

structural rearrangements leads to changes in base pairs, thus errors in transcription, abnormal proteins, and mutations in the individual

105
Q

when does translocation occur

A

when a large segment of DNA breaks from one chromosome and reattaches to a different chromosome, often during meiosis

106
Q

balanced vs imbalanced translocation

A

if its balanced, the translocation does not affect the individual because the amount of genetic material remains the same

if its unbalanced, it will have significant affects due to missing or excessive genes

107
Q

familial down syndrome mutation

A

most frequently encountered translocation
translocation between chromosome 14 and 21

108
Q

deletion

A

removal of part of chromosome

causes mutation

109
Q

duplication

A

doubling part of a chromosome

increases genetic diversity in populations

110
Q

inversion

A

putting piece of chromosome upside down on opposite chromatid

may cause problems with gene expression, histone remodeling due to changed place

111
Q
A

MOD S1 (18 decks)

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