14 15

Question 0

Any of the alternative versions of a gene that may produce distinguishable phenotypic effects

Answer 0

Allele

Question 1

A discreet unit of hereditary information consisting of a specific nucleotide sequence in DNA

Answer 1

Gene

Question 2

An observable heritable feature that may vary among individuals

Answer 2

Character

Question 3

One of two or more detectable variants in a genetic character

Answer 3

Trait

Question 4

An allele that is fully expressed in the phenotype of a heterozygote

Answer 4

Dominant allele

Question 5

An allele whose phenotypic effect is not observed in a heterozygote

Answer 5

Recessive allele

Question 6

The genetic makeup or set of alleles of an organism

Answer 6

Genotype

Question 7

The observable physical and physiological traits of an organism which are determined by its genetic makeup

Answer 7

Phenotype

Question 8

Having two identical alleles for a given gene

Answer 8

Homozygous

Question 9

Having two different alleles for a given gene

Answer 9

Heterozygous

Question 10

A cross between two organisms that are heterozygous for the character being followed

Answer 10

Monohybrid cross

Question 11

Breeding an organism of unknown genotype with a homozygous recessive individual to determine the unknown genotype. The ratio of phenotypes in the offspring reveals the unknown genotype

Answer 11

Test cross

Question 12

Phenotypes if heterozygote and dominant homozygote are indistinguishable

Answer 12

Complete dominance

Question 13

Phenotypes of heterozygote a is intermediate between the two phenotypes of both homozygotes

Answer 13

Incomplete dominance

Question 14

Two alleles each affect the phenotype in separate distinguishable ways

Answer 14

Codominance

Question 15

Phenotype most commonly observed in the natural population

Answer 15

Wild type

Question 16

A gene located on sex chromosomes; usually occurs on X chromosome; fathers transmit this and other x-linked alleles to all daughters but to no sons. Any male who inherits such an allele from his mother will express the trait

Answer 16

Sex-linked gene

Question 17

Production of offspring with combination of traits that differ from those found in either parent

Answer 17

Genetic recombination

Question 18

Reciprocal exchange of genetic material between no sister chromatids during prophase 1 of meiosis

Answer 18

Crossing over

Question 19

An error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from each other

Answer 19

Nondisjunction

Question 20

• Most common lethal genetic disease in US
• Normal allele for this gene codes for chloride transport channels
• Allele is recessive
• if homozygous for this allele then high concentration of extra cellular chloride which causes mucus buildup organs
• if untreated most die before 5th birthday; in US half with this survive to 20s or 30s

Answer 20

Cystic fibrosis

Question 21

• most common inherited disorder among people of African descent
• caused by substitution of a single amino acid in hemoglobin protein
• person homozygous all rbc are sickle shaped: can cause cells to clump as block blood vessels
• regular blood transfusion and new drugs can help or prevent other problems it causes, but no cure
• codominant at molecular level
• disease: both alleles are sickle cell alleles
• trait: one allele normal; one sickle cell
• heterozygous advantage

Answer 21

Sickle cell disease

Question 22

• Degenerative disease of the nervous system
• irreversible and inevitably fatal
• lethal dominant allele no obvious phenotypic effect until individual is 35-45 years old
• Child born to parent with this allele has 50% chance of inheriting the allele and the disorder
• can do genetic testing to see if an individual has this allele in genome

Answer 22

Huntington’s disease

Question 23

• affects 1/3500 males born in US
• progressive weakening of the muscles and loss if coordination
• rarely live past early 20s
• x-linked disorder

Answer 23

Muscular distrophy

Question 24

- x-linked recessive disorder - absence of one or more of proteins required for blood clotting - treat with Iv injections of the protein that is missing

Answer 24

Hemophilia

Question 25

- usually result if extra chromosome 21- each body cell has total of 47 chromosomes - also called trisomy 21 - characteristic facial features, short stature, developmental delays - increased chance if developing many diseases - have life span shorter than normal - frequency increases with age of the mother - most cases result from nondisjunction during meiosis 1

Answer 25

Down's syndrome

Question 26

- XXY - males- testes small and man is sterile - some breast enlargement and other female body characteristics are common - may have subnormal intelligence

Answer 26

Klinefelter syndrome

Question 27

- males- undergo normal sexual development | - tend to be somewhat taller than average

Answer 27

XYY

Question 28

- females; unhealthy - no unusual physical features other than being slightly taller than average - at risk for learning disabilities - fertile

Answer 28

Trisomy X (XXX)

Question 29

- monosomy x (xo) - only known viable monosomy in humans - female; sterile because Sex organs do not mature - when provided with estrogen replacement therapy, do develop secondary sex characteristic - most have normal intelligence

Answer 29

Turner syndrome

Question 30

- results from specific deletion in chromosome 5 - severely intellectually disabled - small head with unusual facial features - cry that sounds like mewing of a distressed cat - usually die in infancy or early childhood

Answer 30

"Cri du chat" cry of the cat

Question 31

- occurs when reciprocal translocation happens during mitosis of cells that will become WBC - exchange of a large portion of chr 22 with small fragment from a tip of chr 9 produces a much shortened chr 22 - causes cancer by activating a gene that leads to uncontrolled cell cycle progression

Answer 31

CML chronic myelogenous leukemia

Question 32

The inactive X in each cell of a female condenses into a compact object called a _____. Most of these genes are not expressed. Females are a mosaic of two types of cells: those with the active X derived from the father and those with the active X derived from the mother

Answer 32

Barr body

Question 33

Genes located on the same chromosome that tend to be inherited together in genetic crosses are said to be _____ genes

Answer 33

Linked

Question 34

Offspring that inherit a phenotype that is different from either parent are said to be ____

Answer 34

Recombinants

Question 35

The reason that linked genes are inherited together is that

Answer 35

They are located on the same chromosome

Question 36

What is the mechanism for the production of genetic Recombinants

Answer 36

Crossing over and independent assortment

Question 37

Males are more often affected by sex linked traits than females because

Answer 37

Males are hemizygous for the X chromosome

Question 38

A man who carries an x linked allele will pass it on to

Answer 38

All of his daughters

Question 39

Which syndrome afflicts mostly males

Answer 39

Duchenne muscular dystrophy

Question 40

If a chromosome lacks certain genes, what has most likely occurred?

Answer 40

Deletion

Question 41

The human trisomy that generally has the most severe impact on the health of the individual is

Answer 41

Trisomy 21

Question 42

What do all human males inherit from their mother?

Answer 42

An X chromosome and mitochondrial DNA

Question 43

False about Down syndrome

Answer 43

It is a sex linked disorder

Question 44

Not true of turners syndrome

Answer 44

They are genetically XXX

Question 45

What results in male sex organs but may have some female body characteristics present?

Answer 45

XXY

Question 46

Not sex linked disorder

Answer 46

Sickle cell anemia

Question 47

What kind of chemical bond is found between paired bases of the DNA double helix

Answer 47

Hydrogen

Question 48

An analysis of the nucleotide composition of DNA

Answer 48

A+C=G+T and G+A=T+C

Question 49

The strands that make up DNA are anti parallel this means:

Answer 49

The 5 to 3 direction of one strand runs counter to the 5 to 3 direction of the other strand

Question 50

What is the function of DNA polymerase

Answer 50

To add nucleotides to the end of a growing DNA strand

Question 51

A cross between homozygous purple flowered and homozygous white flowered pea plants results in offspring with purple flowers. This demonstrates

Answer 51

Dominance

Question 52

Can be dominant or recessive, can represent alternative forms of a gene, can be identical or different for any given gene in a somatic cell

Answer 52

True for alleles

Question 53

The offspring of a cross between two heterozygous purple flowering plants results in

Answer 53

Purple flowered plants and white flowered plants