Genetics

Question 1

The specific location of a gene within a chromosome

Answer 1

locus (plural - loci)

Question 2

Genes that are located close together on the same chromosome. They will not undergo independent assortment during gamete formation, constituting an exception to the law independent assortment. Crossing over sometimes disrupts linked genes on the same chromosome if they are far enough apart.

Answer 2

linked genes

Question 3

A photograph of the chromosomes from an individual cell, usually lined up in homologous pairs, according to size. Missing, extra, or abnormal chromosomes can then be easily identified, aiding the diagnosis of genetic disorders.

Answer 3

karyotype

Question 4

A chromosome involved in defining the sex of an individual. Humans have two ______ and 44 autosomes. In females, both ______ are X chromosomes. Males have one X chromosome and one Y chromosome.

Answer 4

sex chromosome

Question 5

The protective ends of DNA often composed of a short repeated sequence. It is used to prevent degradation or unintended shortening of important genetic coding (exons).

Answer 5

telomere

Question 6

A heterozygote. One who genotypically bears two different alleles for a gene. If one of those alleles is a recessive allele associated with a genetic disorder, the heterozygote will be a ____ for the disorder.

Answer 6

carrier

Question 7

A specific form or possible version of a gene having multiple versions. Alleles may be dominant or recessive.

Answer 7

allele

Question 8

The type of allele that controls phenotype even when a different (recessive) allele is also present, as in heterozygotes. Also the trait or phenotype produced by this allele. Term coined under Mendel’s law of dominance: when two purebreds with different alleles mate, only one allele appears phenotypically.

Answer 8

dominant

Question 9

The fundamental unit of heredity, composed of a stretch of DNA. In general, a single _____ encodes the information needed to produce one kid of protein. Each _____ resides in a specific spot on a chromosome.

Answer 9

gene

Question 10

The entire set of specific alleles present in an organism or cell. The genetic information that (together with the environment) defines the phenotype. Often refers only to the alleles controlling a particular trait of interest.

Answer 10

genotype

Question 11

The genetic transmission of traits from parents to offspring, resulting in offspring resembling their parents. Traits transmitted this way are called hereditary traits.

Answer 11

heredity

Question 12

The entire set of observable characteristics of an organism or cell; the physical traits of an organism. The genotype, together with environmental factors, defines it.

Answer 12

phenotype

Question 13

The specific DNA sequence to which proteins can bind in order to initiate DNA synthesis.

Answer 13

origin of replication

Question 14

A genetic mixture; the offspring. of two genetically different parents. Hybrids are usually heterozygous for a variety of genes.

Answer 14

hybrid

Question 15

An individual with the same allele on both homologous chromosomes. The opposite is heterozygous. Mating of two individuals with the _____ genotype will produce only offspring with that genotype. The two identical alleles may be dominant or recessive. (eg. RR or rr)

Answer 15

homozygous

Question 16

A situation in which an individual (heterozygote) possesses two dissimilar alleles for the same gene. The opposite is homozygous

Answer 16

heterozygous

Question 17

A haploid sex cell (either an egg or sperm cell). Male and female gametes join during fertilization to create a diploid zygote. ____ are created out of germ cells and are passed down to offspring.

Answer 17

gamete

Question 18

The first generation of offspring from a cross between two varieties or individuals. In Mendel’s experiments, all the ____ offspring were heterozygous hybrids with a dominant phenotype.

Answer 18

F1 generation.

Question 19

The second generation of offspring in a breeding experiment; the offspring from a mating between two F1 hybrids. In Mendel’s monohybrid experiments, the ratio of dominant to recessive phenotypes in the F2 generation was 3:1.

Answer 19

F2 generation

Question 20

The functional part of a nucleic acid sequence that codes for amino acid sequences (proteins).

Answer 20

exon

Question 21

The retention of three copies of a chromosome. Often referred to in relation to Down’s syndrome, a genetic disease caused by ____ trisomy of the twenty-first chromosome.

Answer 21

trisomy

Question 22

Any observable feature or characteristic of an organism.

Answer 22

trait

Question 23

The test breeding of parents that differ in tow characteristics.

Answer 23

dihybrid cross

Question 24

Refers to an allele that cannot control phenotype unless it is the only kind of allele present, as in a homozygote or hemizygote. Refers to the trait or phenotype produced when only a ____ allele is present. The opposite of _____ is dominant.

Answer 24

recessive

Question 25

A pictorial method of showing the gene combinations (genotypes) of offspring that might result from an experimental genetic cross of two parents.

Answer 25

Punnett square

Question 26

Mendel's conclusion in his first law that individuals have two copies of each gene, and that these copies separate randomly during gamete formation, one per gamete. This holds true except with sex chromosomes, because males have only one copy of the female X gene.

Answer 26

segregation

Question 27

The term for genes on a sex chromosome, or to traits defined by such genes. Such traits are transmitted by gender. Recessive _____ traits such as hemophilia and color-blindness must be inherited from both parents in females, but only from the mother in males.

Answer 27

sex-linked

Question 28

Multiple genes cumulatively creating a single effect.

Answer 28

polygenic inheritance

Question 29

Multiple effects caused by just one gene.

Answer 29

pleiotropy

Question 30

A family tree that lists the inheritance of traits across several generations.

Answer 30

pedigree

Question 31

The phenomenon that occurs when a pair of homologous chromosomes fails to separate during gamete formation. The offspring produced from these gametes have either one too many or one too few of a particular chromosome. ______ is the cause of genetic disorders like Down's syndrome.

Answer 31

nondisjunction

Question 32

An error in the sequence of DNA or RNA nucleotides that may affect protein coding. Substitution ______ occur when one nucleotide is replaced by another. Frame shift _____ occur when a nucleotide is either inserted or deleted into the code, drastically altering every codon.

Answer 32

mutation

Question 33

An agent that causes mutation, or the alteration of coding on a DNA sequence.

Answer 33

mutagen

Question 34

The test breeding of parents that differ in one characteristic.

Answer 34

monohybrid cross

Question 35

The principle that different genetic traits (alleles) separate independently of each other (pending their location on separate homologous chromosomes).

Answer 35

Mendel's second law (independent assortment)

Question 36

The principle that the two variants of a genetic trait (alleles) separate during the formation of gametes.

Answer 36

Mendel's first law (segregation)

Question 37

(Born 1822 - Died 1884) Was an Austrian monk and scientist. Through a series of experiments with pea plants, he discovered the basic laws of heredity, including dominance, segregation and independent assortment.

Answer 37

Gregor Mendel

Question 38

The nonsense parts of a nucleic acids sequence found in-between exons.

Answer 38

intron

Question 39

An observation from Mendel's second law that during gamete formation, segregation of one pair of genes has no influence over the segregation of another pair. Two different traits will be inherited independently of one another. This holds true for all but linked genes.

Answer 39

independent assortment

Question 40

The phenomenon that occurs when two different alleles of the same gene are both partially expressed in a heterozygote. The resulting phenotype is intermediate between the homozygous phenotypes of the two alleles. Color in a four o'clock flower is an example of this.

Answer 40

incomplete dominance

Question 41

A phenomenon in which two alleles of the same gene are fully expressed in the phenotype when both are present in the heterozygote. Blood type is an example of this.

Answer 41

codominance

Question 42

Any chromosome that is not a sex chromosome. Humans have 44 _____, in 22 homologous pairs. The two sex chromosomes comprise the twenty-third pair of chromosomes.

Answer 42

autosome