Human Genetics

Front 1

Mutation

Back 1

a heritable change in DNA that can occur in any body cell; can be caused by environmental factors

Front 2

Somatic Cell Mutations

Back 2

passed on to daughter cells through cell division

*not transmitted to future generations

Front 3

Germ Cell Mutations

Back 3

passed on to future generations

Front 4

Mutation Detection Methods

Back 4

1. Pedigree Analysis

2. Calculating Mutation Rates

Front 5

Pedigree Analysis

Back 5

used to reveal potential inheritance patterns; can help identify the individual in whom the mutation arose

Front 6

Calculating Mutation Rate

Back 6

# of mutant alleles per locus per generation

Front 7

Queen Victoria

Back 7

passed the x-linked recessive trait of hemophilia on to three of her nine children

- most likely heterozygote

Front 8

Mutation Rate Factors

Back 8

- gene size

- presence of specific nucleotide repeats

- spontaneous or environmentally induced chemical changes

Front 9

Achondroplasia

Back 9

form of dwarfism caused by a dominant mutation

Front 10

Spontaneous Mutation Causes

Back 10

1. errors in normal cellular processes

i.e DNA replication

2. natural change in molecular structure of bases in DNA

Front 11

Induced Mutation Causes

Back 11

mutagens that affect DNA & cellular processes

i.e. radiation & chemicals

Front 12

Spontaneous Mutations:

Errors in DNA Replication

Back 12

DNA polymerase incorrectly reads nucleotide sequence & adds a mis-paired nucleotide

Front 13

Tautomeric Shift

Back 13

small chemical change in bases that enables hydrogen bonding with non-complementary bases

*can cause mutation

Front 14

Sources of Radiation in U.S.

Back 14

1. radon (54%)

2. x-rays & internal (11%)

3. terrestrial & cosmic (8%)

Front 15

Base Analog 5-Bromouracil

Back 15

displays structural similarities to thymine & is sometimes inserted during replication leading to mutations

Front 16

Converting Cytosine to Uracil

Back 16

chemical mutagens can remove NH2 amino group & convert cytosine into uracil leading to mutation

Front 17

Nucleotide Substitution

Back 17

replacement of one or more nucleotides in a DNA sequence

Front 18

Types of Nucleotide Substitutions

Back 18

1. Missense

2. Sense

3. Nonsense

4. Frameshift

Front 19

Missense

Back 19

a single amino acid substitution

Front 20

Sense

Back 20

changes a termination codon into an amino acid

Front 21

Nonsense

Back 21

changes an amino acid into a termination codon

Front 22

Frameshift

Back 22

insertion or deletion of one or more nucleotides other than in multiples of three

- alter the reading frame

- change amino acids in the protein

Front 23

Hemoglobin Mutations

Back 23

missense mutations in codon 6

Front 24

Fragile-X Syndrome

Back 24

x-linked inherited form of mental retardation caused by expanded # of CGG repeats in the FMR-1 gene

- more than 230 repeats

- normal = 6 to 52

Front 25

Mutation Repair in Humans

Back 25

human genome contains more than 175 DNA repair genes due to high mutation rates; system can be overloaded

Front 26

DNA Damaged Cell Fates

(excess)

Back 26

1. Dormancy

2. Apoptosis

3. Become Cancerous

Front 27

DNA Repair Systems

Back 27

i. proofreading during DNA replication

ii. recognizing wrong base insertions

iii. repairing DNA damage from UV light

Front 28

Xeroderma Pigmentosum

Back 28

example of a genetic disorder that can affect DNA repair system function

Front 29

Proofreading

Back 29

enzyme DNA polymerase detects mismatched base pair - reverses/removes nucleotide from DNA strand - inserts correct nucleotide & resumes synthesis of new strand

Front 30

Sickle Cell Anemia

Back 30

caused by a specific single nucleotide substitution

Front 31

Cystic Fibrosis

Back 31

can be caused by various mutations in a single CFTR gene

- deletions

- nucleotide substitutions

- frameshifts

Front 32

Epigenetics

Back 32

heritable chemical modification to DNA & its associated proteins that affects gene expression without changing the nucleotide sequence

Front 33

Epigenetic Trait

Back 33

phenotype produced by epigenetic changes to DNA

Front 34

Epigenome

Back 34

the epigenetic state of a cell that can change many times throughout lifespan due to environmental conditions

Front 35

Epigenetic Factors

Back 35

1. methyl groups

2. acetyl groups

3. phosphate groups

Front 36

DNA Methylation

Back 36

a methyl group can tag DNA & activate or repress genes

Front 37

Histone Modification

Back 37

binding of epigenetic factors to histone tails - alters the extent of which DNA is wrapped around histones & accessibility of genes in DNA

Front 38

Nucleosomes & Gene Expression

Back 38

1. DNA winds around histone to form a nucleosome

2. Promoters wrapped tightly in histones are unavailable for RNA polymerase & are not expressed

3. Chemical modification of histones loosens DNA making promotor available for transcription

Front 39

Genetic Imprinting

Back 39

reversible modification of DNA that affects expression of the chemically modified gene; selective expression of either the maternal or paternal allele