Chapter 20 Chromosomes And Human Genetics

Front 1

Cystic Fibrosis is..?

Back 1

a fatal genetic disorder

Front 2

cause of CF?

Back 2

a gene on chromosome 7 that provides the instructions for building a plama membrane protein called CFTR

Front 3

CF is a result of

Back 3

a faulty CFTR gene is inherrited from both parents

Front 4

CF is usually fatal before..?

Back 4

the age of 30

Front 5

symptoms of CF

Back 5

thickened mucus clogs airways, infections develop from bacteria growing in the mucus (normally die of infections)

Front 6

people who are ___ are guaranteed to get CF

Back 6

homozygous recessive

Front 7

treatments for CF

Back 7

physiotherapy- thumping on the back and chest to loosen mucus
antibotics-to cure infections

Front 8

gene-chromosome connections

Back 8

1.particular locus for each gene
2.a diploid cell has homologous pairs of chromosomes:one from each parent
3.crossing over occurs during meiosis
4.genes in a diploid cell have two alleles
5.independent assortment of chromosomes

Front 9

linkage

Back 9

distance is short between chromosomes they are "linked"

Front 10

the closer chromosomes are

Back 10

less likely to be seperated during crossing over, tend to stay together

Front 11

karyotype

Back 11

visualizes the chromosomes/gives a portrait of chromosomes in a cell

Front 12

a karyotype is..?

Back 12

the outward appearance of chromosomes

Front 13

in a karyotype you..

Back 13

extract cells and grow in tissue cultures

Front 14

once cell is culture is established what is added?

Back 14

colchicine is added to stop mitosis at metaphase

Front 15

after the colchince is added..?

Back 15

centrifuge to move cells to bottom of the test tube, add saline and a fixative to the cells

Front 16

last step for karyotype

Back 16

visualize under microscope, photograph one cell, enlarge picture, arrange chromsomes

Front 17

sex chromosomes carry?

Back 17

genes associated with sexual traits

Front 18

human sex chromosomes

Back 18

x chromosome and y chromosome

Front 19

X chromosome

Back 19

x chromosome- XX (female), most genes deal with nonsexual characteristics, genes refered to as X-linked genes

Front 20

Y chromosome

Back 20

Y chromosomes- XY(male), gender determined by SRY gene(when gene is expressed testes form in the embryo), genes are refered to as Y-linked genes

Front 21

females have two x chromosomes, are both active?

Back 21

one x is inactivated

Front 22

x inactivation

Back 22

most or all of one of a females x chromosomes are turned off soon after first division of zygote, inactivated x is condensed into a Barr body

Front 23

incontinentia pigmenti

Back 23

x-linked disorder, darker patches of skin are visible in tissue where the mutated x chromosome is active

Front 24

sex influenced traits

Back 24

appear more often in one gender than the other

Front 25

where are genes for sex influence traits located?

Back 25

on autosomes

Front 26

example of sex influenced trait

Back 26

patterened baldness, males are heterozygous, females must be homozygous recessive

Front 27

sex-limited genes

Back 27

males and females inherit the same genes (on the x chromosome) but only the genes appropriate for the persons gender are turned on

Front 28

example of sex-limited genes

Back 28

mans beard or a womans breast

Front 29

pedrigee chart

Back 29

tracks several generations of a family, showing who exhibited the trait being investigated

Front 30

pedrigees are often used to?

Back 30

identify those at risk of trasmitting or developing the trait in question

Front 31

huntingtons disease

Back 31

nervous system progressively deteriorates

Front 32

Who constucted a pedigree for a huge family in venezuela? (about 10000 people)

Back 32

Nancy Wexler

Front 33

genetic abnormality

Back 33

deviation from the average (6 toes)

Front 34

genetic disorder

Back 34

causes mild to severe medical problems

Front 35

syndrome

Back 35

set of symptoms that usually occur together are characterize a disorder

Front 36

humans are carries of how many lethal genes?

Back 36

3-8 lethal genes

Front 37

genetic analysis

Back 37

determine genotype or each parent
use family pedigrees
one the extent of the risk has been deteremined is is the same for each pregnancy

Front 38

recessive alleles:
parents are heterozygous
parents are homozygous

Back 38

hetero- 25% chance of offspring being homozygous recessive
homo- 100% of the offsping will have the trait

Front 39

Inherited recessive traits on autosomes cause what disorders?

Back 39

cystic fibrosis, phenylketonuria, tay sachs disease

Front 40

Cystic Fibrosis

Back 40

faulty CFTR gene

Front 41

Phenylketonuria

Back 41

abnormal build up of the amino acid phenylalanine (phe), possible mental retardation, diet should be low in phe

Front 42

tay-sachs disease

Back 42

lacking hexosaminidase, symptoms- lose motor function, become deaf blind or mentally retarded
death usually occurs in early childhood
most common among children of eastern european jewish descent

Front 43

Autosomal dominant disorders

Back 43

dominant allele expressesed even in heterozygotes

Front 44

offspring of a heterozygous parent and normal homozygous recessive parents

Back 44

50% likely to be heterozygous

Front 45

severity of autosomal dominant disorders varies with the

Back 45

condition

Front 46

disorders due to dominant genes

Back 46

huntingtons disease, marfan syndrome, achondroplasia, familial hypercholesterolemia

Front 47

huntingtons disease

Back 47

symptoms appear after age 30:fatal
mutation on chromosome 4

Front 48

marfan syndrome

Back 48

defective form of protein fibrilin
symptoms include weakening of the wall of the aorta
about 1 in 5000 humans have marfan syndrome

Front 49

achondroplasia

Back 49

cartilage of limb bones doesnt develop properly
short stature

Front 50

familial hypercholesterolemia

Back 50

leads to elevated blood levels and cholesterol

Front 51

genes on the x chromosome also are inherrited according to..?

Back 51

predictable patterns

Front 52

who are affected more?

Back 52

many more males than females

Front 53

why are females less affected?

Back 53

a recessive x allele can be masked in females

Front 54

who do daughters receive the affected allele from?

Back 54

an affected father

Front 55

disorders that are recessive x linked traits

Back 55

hemophilia,duchenne muscular dystrophy (DMD), red/green color blindness

Front 56

hemophilia

Back 56

two types: hemophilia A and hemophilia B

Front 57

hemophilia A

Back 57

most common form
mutation in the gene for clotting protein factor VIII

Front 58

hemophilia B

Back 58

mutation in the gene for clotting protein factor IX

Front 59

why did queen victorias family have a higher frequency of hemophilia?

Back 59

due to marriage between close relatives

Front 60

duchenne muscular dystrophy (DMD)

Back 60

mutation in gene that encodes the protein dystrophin
weak muscles:break down of muscles
death usually begins at age 20 due to cardiac repspitory failure

Front 61

red/green color blindess

Back 61

mutation in the gene tat encodes for the protein opsin
genes for opsin and blood clotting factor VIII are closely linked

Front 62

Rare X-linked abnomalities

Back 62

faulty enamel trait, testicular feminizing syndrome

Front 63

faulty enamel trait

Back 63

dominant x-linked allele
improper development of tooth enamel

Front 64

testicular feminizing sydrome

Back 64

XY individual develops as a female externally
mutation on the X chromosome produces defective receptors for male hormones

Front 65

what are factors that complicate genetic analysis?

Back 65

genetic analysis is a difficult task
may be necessary to combine pedigrees of similar families
research will yield more information about genetic disorders

Front 66

pharmacognetics

Back 66

identify genes that control common reactions to various drugs

Front 67

what would an idividual need?

Back 67

a genetic profile

Front 68

what could the physician select?

Back 68

the best drugs for that individual illness, improve patient care

Front 69

gene mutation

Back 69

change in one or more of the nucleotides that make up a gene

Front 70

various changes in chromosomes that could cause genetic disorders

Back 70

deletion, duplications, translocation, inversion

Front 71

what does deletion of part of a chromosome cause?

Back 71

spontaneous, viral, irradiation, chemical, or enviormental
permanent loss of genetic material

Front 72

cri-du-chat

Back 72

one deletion of chromosome 5
abnormal mental development
misshapen larynx

Front 73

duplications

Back 73

gene sequences that are repeated

Front 74

translocations

Back 74

part of one chromosome exchanges places with corresponding part of a nonhomologous chromosome
rare cancers including leukemia

Front 75

philidelphia chromosome

Back 75

extra-long chromosome 9 due to a piece of chromosome 22
(9/22 translocation)

Front 76

inversion

Back 76

a segment of a chromosome is inverted 180 degrees

Front 77

aneuploidy

Back 77

embryo does have have an exact multiple of 23 chromosomes

Front 78

polyploidy

Back 78

embryo has three four or more set of 23 chromosomes (3n, 4n)

Front 79

when can chromosome numbers change?

Back 79

during mitosis, meiosis, or fertilization

Front 80

what is a common cause of abnormal numbers or autosomes?

Back 80

nondisjunction

Front 81

nondisjunction

Back 81

one or more pairs of chromosomes fails to seperate during cell division
increases with a womans age
if such a gamete is fertalized:
trisomy-3 of a certain chromosome
monosomy- one

Front 82

down syndrom, trisomy 21

Back 82

metal retardation, abnormal skeletal development, motor functions delayed, and weaker muscles

Front 83

what can nondisjunction also change?

Back 83

number of sex chromosomes

Front 84

turner syndrome (X)

Back 84

missing an x chromosome: XO
female: webbed neck, no secondary sexual traits at puberty, sterile, may age prematurely

Front 85

poly-X female (XXX, XXXX)

Back 85

XXX develop normally (tend to be tall and thin)
XXXX severely mentally challenged

Front 86

klinefelter syndrome (XXY)

Back 86

low fertility, metal retardation, small testes, sparse body hair, enlarged breasts
testosterone injections may reverse phentype

Front 87

jacobs syndrome (XYY)

Back 87

taller
normal male phenotype
severe acne
speech and reading problems

Front 88

non-disjuction that can lead to change in number of sex chromosomes

Back 88

turner syndrome (X), poly-X female (XXX, XXXX), klinefelter syndrome (XXY), jacobs syndrome (XYY)

Front 89

genetic disorders can result from?

Back 89

nondisjunction of x chromosomes