Path 404 Sp 2008 Genetics In Health And Disease

Front 1

How many essential molecular subunits or bases make up the human genome?

Back 1

4 (A,G,T,C)

Front 2

What does base "A" represent?

Back 2

adenine

Front 3

What does base "T" represent?

Back 3

thymine

Front 4

What does base "G" represent?

Back 4

guanine

Front 5

What does base "C" represent?

Back 5

cytosine

Front 6

Which of the four bases are paired?

Back 6

A to T, C to G

Front 7

How many chromosomes are there in a normal human cell?

Back 7

46 (22 pairs of autosomes, plus sex chromosomes X and Y)

Front 8

centromere

Back 8

the central constriction of a chromosome, between the short (p) and the long (q) arms

Front 9

telomere

Back 9

the ends of the chromosome (typically gene-rich regions)

Front 10

regulatory sequences

Back 10

promoters, enhancers, etc. that tell a gene when, where, how rapidly, how long, and to what stimuli it should function

Front 11

start codon

Back 11

denotes the beginning of the protein coding sequence

Front 12

first exon

Back 12

usually contains the start codon

Front 13

exon

Back 13

the transcribed and translated "coding" regions of a gene

Front 14

intron

Back 14

intervening sequences that do not code for the protein; not part of the mature RNA (mRNA) that is used to make the protein

Front 15

splicing

Back 15

removal of introns in the generation of mature mRNA

Front 16

last exon

Back 16

contains the last codons used in the synthesis of the protein as well as the stop codon ("off switch")

Front 17

What is the primary function of a gene?

Back 17

produce proteins

Front 18

central dogma

Back 18

DNA---transcription--->mRNA---translation--->protein

Front 19

What three categories of functions do proteins serve in the body?

Back 19

structural, functional, and regulatory

Front 20

alleles

Back 20

alternative forms of a given gene

Front 21

codominant

Back 21

both traits are expressed in the heterozygous state (ex. AB blood group)

Front 22

dominant

Back 22

a trait that is fully expressed in the heterozygous state

Front 23

expression

Back 23

realization of the functional activity of a gene (doesn't occur if regulatory mechanisms "turn it off"; can vary from tissue to tissue or time to time)

Front 24

expressivity

Back 24

variable nature or severity of clinical phenotype in individuals with the same mutation (variable expressivity is common in autosomal dominant traits)

Front 25

gene

Back 25

the unit of heredity; now known to consist of DNA molecules arrayed on chromosomes

Front 26

genetics

Back 26

the study of heredity and the principles and molecular basis of inheritance

Front 27

genotype

Back 27

the allelic makeup of an individual, either in its entirety or at a given locus

Front 28

heterozygous

Back 28

the two alleles in a given pair are different

Front 29

homozygous

Back 29

the two alleles in a given pair are identical

Front 30

linkage

Back 30

traits or alleles which occur together more often than expected, usually because their loci are near each other on the same chromosome

Front 31

locus

Back 31

the physical location of a gene on a chromosome

Front 32

mutation

Back 32

an alteration in the DNA sequence which changes the sequence or number of amino acids in the protein product

Front 33

penetrance

Back 33

the proportion of individuals with a specific genotype who exhibit the associated phenotype (ex. incomplete penetrance = "skipping generations")

Front 34

phenotype

Back 34

the appearance of a particular characteristic or set of characteristics in an individual (ex. height, weight, intelligence, physical characteristics, pigmentation, blood pressure, glucose levels, disease states, etc.)

Front 35

polymorphism

Back 35

variation in DNA (usually refers to a variation of no clinical significance)

Front 36

recessive

Back 36

a trait that is not expressed in the heterozygous state

Front 37

semidominant

Back 37

a trait that is intermediate in the heterozygous state (ex. red x white=pink flowers)

Front 38

splicing

Back 38

removal of introns in the generation of mature mRNA

Front 39

thresholds

Back 39

define many disorders; value beyond which a trait is considered harmful (mental retardation IQ<70)

Front 40

List three types of mutations

Back 40

1. those which alter the amino acid sequence and protein fuction (ex. enzyme kinetics, regulatory genes)
2. those which stop transcription prematurely, truncating the protein product
3. those which affect the rate of transcription, efficiency of splicing, etc. and slow down or speed up protein synthesis

Front 41

Do X-linked traits appear more often in males or females?

Back 41

males

Front 42

contiguous gene syndromes

Back 42

caused by absence or dysfunction of a series of genes clustered together on the same chromosome

Front 43

Name the four types of gene defects

Back 43

single gene disorders, contiguous gene syndromes, abnormalities of chromosome structure, abnormalities of chromosome number

Front 44

Can an X-linked trait be passed from father to son? Mother to son?

Back 44

no, yes

Front 45

simple traits

Back 45

determined by a single gene in Mendelian fashion

Front 46

complex traits

Back 46

determined by multiple genes, some of which may be stronger determinants that others, often in concert with nongenetic (environmental) factors

Front 47

aneuplouidy

Back 47

wrong number of chromosomes

Front 48

trisomy

Back 48

3 copies of one chromosome (one extra)

Front 49

monosomy

Back 49

1 copy of a chromosome (one missing)

Front 50

Down Syndrome
1. What type of aneuploidy?
2. List effects of DS
3. Does risk increase or decrease with mother's age?

Back 50

1. trisomy 21 (47,XX + 21)
2. mental retardation, short stature, distinctive physical appearance, high risk of heart defects, thyroid disease, Alzheimer disease
3. increase

Front 51

Turner Syndrome
1. Type of anueploidy
2. Typically affects males or females?
3. List effects of TS

Back 51

1. Monosome (X - 45, X)
2. Females
3. infertility due to abnormal development of the ovaries, short stature, broad neck, rick of hearing problems, heart and kidney defects

Front 52

Major Predisposing Gene

Back 52

familial breast and ovarian cancer due to BRCA mutations

Front 53

Multifactorial

Back 53

interaction of multiple predisposing genes and environmental factors probably accounts for most common medical conditions

Front 54

What six factors may "disease genes" determine?

Back 54

1. likelihood of getting disease in the first place
2. severity
3. rate of progression
4. likelihood of specific complications
5. responses to therapies
6. complications of therapies

Front 55

What three common conditions predispose people to disease?

Back 55

obesity, hypertension, behavioural dysfunctions

Front 56

What have we learned? What have we really learned?

Back 56

1. It's not a matter of nature vs. Nurture, but Nature and Nurture together which cause most common diseases and produce most human traits.
2. David Wargowski has a monotone voice.