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My BIO DAT Prep > Hereditary > Flashcards

Hereditary Flashcards

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Biology 101 flashcards
1
Q

p21

A
  • Tumor suppressor gene
  • inhibits cyclin dependent kinase (CDK) activity —> decreases the frequency of cell division (CDK stimulates cell division; p21 inhibits phosphorylation activity in order to decrease excessive cell division)
  • Haplosufficient
  • Important gene in regulating cancer by regulating cell division
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2
Q

Which chromosome are the majority of sex-linked disorders passed down through?

A

Due to the size difference, the majority of sex-linked disorders are passed down through X-chromosome linkage

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3
Q

Down syndrome

A

trisomy at chromosome 21
a result of nondisjunction at chromosome 21, producing a zygote with 2n+1 (47) chromosomes
it is a trisomy that is non-fatal —> the altered chromosomes does not kill the embryo

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4
Q

Haplotype

A

A group of genes that are located so close to each other on a chromosome that they tend to be inherited together
Because the genes are clustered together, they tend to not be split via crossing over (recombination event) and are often found in offspring

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5
Q

p53

A

A tumor suppressor gene
Plays numerous roles in cancer prevention
upregulated (increase in its protein production) in response to cell stress

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6
Q

One loss-of-function mutation in p53 would result in what?

A

No effect
Loss-of-function in both copies of the genes are required for cancer causing, null tumor suppressor alleles

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7
Q

Pleiotropy

A

When one gene affect many different traits

Ex: cystic fibrosis
A single gene will lead to the expression of cystic fibrosis, a disease that cause the expression of different symptoms in different tissues

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8
Q

Epistasis

A

An interaction between genes where one gene affects the expression of different genes

Ex: hair varieties

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9
Q

Heterozygous organisms

A

Organisms that posses a dominant allele on one of their homologous chromosomes (homolog) and a recessive allele (for the same gene) on the other homolog

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10
Q

Heterozygous organism

A

Organisms that posses a dominant allele on one of their homologous chromosomes (homologs) and a recessive allele (for the same gene) on the other homolog

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11
Q

During crossing over, what structures do homologous chromosomes form when they physically join together?

A

Form a tetrad (or bivalent)
Occurs doing prophase of meiosis I

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12
Q

Allele

A

Variance of a gene that has different forms
Found on the same loci on both chromosomes in a homologous pair
Ex: various color alleles at the eye color gene locus, such as brown eyes or blue eyes

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13
Q

Oncogenes

A

Genes that can transform a normal cell into a cancerous cell

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14
Q

Test cross

A

Used t determine an unknown parental genotype, based on the phenotypes seen in the offspring generations
One parents of an unknown genotype will be bred with a parent that is phenotypically recessive with genotype homozygous recessive

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15
Q

Turner syndrome

A
  • X chromosome monosomy that only affects females
  • A female will have one X chromosome (deletion of one X chromosome), leading to 2n-1 (45) chromosomes
  • Usually does not cause any intellectual disability’s but it does lead to physical abnormalities and sterility- short stature, gonadal dysgenesis, heart defects, kidney abnormalities
  • XO genotype
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16
Q

Proto-oncogenes

A

Genes involved with control and regulation of cell division and can become oncogenes (cancer-causing genes) due to gain-of-function mutation
Follow the one-hit-hypothesis

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17
Q

One-hit-hypothesis

A

A gain-of-function mutation in one copy of the gene is enough to produce a mutant phenotype (turns into an oncogene)

Proto-oncogene + gain-of-function mutation = oncogene

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18
Q

Gain-of-function mutations

A

Can cause too much protein to be made which results in over expression of a gene or production of an over-active protein which results in an increase in gene product activity, cancerous growth occurs as a result

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19
Q

Two-hit hypothesis

A

Loss-of-function mutations in both copies of the gene are needed to produce a mutant phenotype (cancer causing)

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20
Q

Haploinsufficiency

A

When one copy of the gene is lost or nonfunctional and the expression of the remaining copy is not sufficient enough to result in a normal phenotype- it can result in an intermediate phenotype
The normal trait requires two functional gene copies to produce enough protein to show the trait

21
Q

Haplosufficiency

A

One copy of the gene is sufficient enough to achieve a normal phenotype because it produces enough protein to show the trait
The normal trains only requires one functional copy

22
Q

During DNA methylation, where are the methyl groups added to the genome?

A

to the nitrogenous bases on a DNA strand

23
Q

what is the function of DNA methylation?

A

inhibiting gene expression by two mechanisms:
1) blocking transcription from occurring by preventing transcription proteins from binding to the DNA strand
2) DNA that has been methylated can wrap tightly around histones through the recruitment of specific proteins, preventing access to methylated DNA

24
Q

what is DNA demethylation?

A

the removal of the methyl group on the nitrogenous base which results in increased gene expression (gene upregulation)

opposite of DNA methylation which upregulats

25
Q

what is histone acetylation?

A

the addition of an acetyl group to the amino acid lysine found in the histone tails that protrude from one histone core

26
Q

what is the result of histone acetylation?

A

causes DNA to wrap less tightly around histones, leading to an increase in gene expression –> weakens the electrostatic affinity/interaction between DNA and histone proteins due to histones becoming less positive
*associated with euchromatin

27
Q

what epigenetic regulation is present in the inactive X chromosome of females compared to the active X chromosome?

A

DNA methylation: the inactive X chromosome is heavily methylated compared to the active DNA regions –> this is known as the barr body (located on the periphery of the ell nucleus)

28
Q

prader-willi syndrom

A
  • occurs due to genomic imprinting
  • a set of genes on chromosome 15 inherited from the mother are inactivated, while the same genes on the copy of chromosome 15 inherited from the father are left active
  • occurs when the genes on the paternal copy of the chromosome are deleted or mutated and the child does not have active gene expression from either chromosome
29
Q

what is genomic imprinting?

A
  • the alteration in expression of a gene is dependent on which parent the gene was inherited from
  • only one allele of the gene is expressed –> the genes on a chromosome from one parent are imprinted (silenced via DNA methylation) while genes on the chromosome from the other parent are expressed (activated via histone acetylation)
30
Q

histones

A
  • positively charged, basic proteins
  • organize and condense DNA
  • bond between (+) histones and (-) DNA is an ionic bond
31
Q

transcriptome

A
  • the entire set of mRNA expressed by a cell
32
Q

proteome

A
  • entire set of proteins expressed by a cell
33
Q

sanger sequencing

A
  • amplification of DNA and use of fluorescence to determine the order of the genetic sequence
34
Q

cri du chat

A

caused by deletion on chromosome 5

35
Q

klinefelter’s syndrom

A
  • caused form an extra X chromosome leading to an XXY genotype
36
Q

how can a fetus be tested for genetic disorders?

A
  • amniocentesis or
  • chorionic villus sampling (CSV)
37
Q

what are 3 sex-linked recessive conditions?

A
  • hemophilia
  • color blindness
  • Duchenne’s muscular systrophy
38
Q

hemophilia

A
  • sex-linked recessive condition
  • causes abnormal blood clotting
39
Q

color blindness

A
  • sex-linked recessive disorder
  • primarily observed in males
40
Q

duchenne’s muscular dystophy

A
  • sex-linked recessive disorder
  • progressive loss of muscle
41
Q

phenylketonuria (PKU)

A
  • autosomal recessive disorder
  • inability to produce the proper enzymes for phenylalanine breakdown
  • causes degradation product, phenylpyruvic acid to accumulate
42
Q

cystic fibrosis

A
  • autosomal recessive disorder
  • causes fluid builduo in respiratory tract
43
Q

tay-sachs

A
  • autosomal recessive disorder
  • lysosome defect in which cells can’t breakdown lipids for normal brain function
44
Q

huntington’s disease

A
  • autosomal dominant disorder
  • nervous system degeneration
45
Q

achondroplasia

A
  • autosomal dominant disorder
  • causes dwarfism
46
Q

hypercholesterolemia

A
  • autosomal dominant disorder
  • excess cholesterol in blood that progresses into theart disease
47
Q

viroids

A
  • smaller than viruses
  • circular RNA molecules that infect plants
  • they do not encode for proteins, they replicate in host plant cells via host enzymes
  • cause errors in the regulatory system of plant growth
48
Q

prions

A
  • not virus or cell
  • infectious, mis-folded versions of proteins in the brain
  • cause normal versions of proteins to become mis-folded
  • fatal
  • implicated in diseases like mad cow, kuru, scrapie the sheep and creutzfeldt-jakob disease
49
Q

retrovirus

A
  • single-stranded RNA virus
  • uses reverse transcriptase to make complement DNA from their RNA by hijacking the host cells replicating machinery
  • the RNA is then used to manufacture mRNA or enter the lysogenic cycle (encorperated into host cell)
  • ex: HIV

My BIO DAT Prep (24 decks)

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