Genetics

Question 1

Gene

Answer 1

the basic unit of heredity

Question 2

Chromosomes

Answer 2

where genes are located

Question 3

Alleles

Answer 3

the alternative forms of multiple genes

Question 4

Genotype

Answer 4

the genetic makeup of an individual

Question 5

Phenotype

Answer 5

the physical manifestation of the genetic makeup of an individual

Question 6

Law of Segregation

Answer 6

• genes exist in alternative forms
• an organism has two alleles for each inherited trait (one from each parent)
• two alleles segregate during meiosis
• the expressed allele is the dominant one and the silent allele is the recessive
• organisms that contain two copies of the same allele are homozygous & organisms that carry two different alleles are heterozygous
• the dominant allele is expressed in the phenotype

Question 7

Monohybrid Cross

Answer 7

• applies when only one trait is being studied in the particular mating
• parental generation: the individuals being crossed
• filial generation: the progeny generations

Question 8

Punnett Square

Answer 8

• a way of predicting the genotypes expected from a cross drawing

Question 9

Test Cross

Answer 9

-a diagnostic tool used to determine the genotype of an organism

Question 10

Law of Independent Assortment

Answer 10

the inheritance of one such trait is completely independent of one another

Question 11

Incomplete Dominance

Answer 11

if the phenotype of heterozygate is an intermediate of the phenotypes of the homozygates, blending occurs

Question 12

Codominance

Answer 12

occurs when multiple alleles exist for a given gene and more than one of them is dominant, there is no blending

Question 13

Sex Determination

Answer 13

• most chromosomes exist as pairs of homologous called autosomes
• all humans have 22 pairs of autosomes
• women: XX men: XY
• sex linked: genes located on the X or Y chromosomes

Question 14

Sex Linkage examples

Answer 14

homophilia or color-blindness

Question 15

Environmental Facts

Answer 15

• can affect the expression of a gene
• interaction between the environment and the genotype produces the phenotype
• temperature also influences the hair color

Question 16

Cystoplasmic Inheritance

Answer 16

cytoplasmic genes may interact with nuclear genes and are important in determining the characteristics of their organelles

Question 17

Nondisjunction

Answer 17

the failure of homologous chromosomes to separate properly during meiosis I or the failure of sister chromatids to separate during meisois II

Question 18

Chromosomal Breakage

Answer 18

may occur spontaneously or be induced by environmental factors

Question 19

Mutations

Answer 19

• changes in the genetic information coded in the DNA of a cell
• in somatic cells, it can lead to tumors
• in sex cells (gametes), it will be passed down to offspring

Question 20

Mutagenic agents

Answer 20

• induce mutations (x-rays, UV rays, and radioactivity)
• inhibit spindle formation
• can be carcinogenic

Question 21

Point Mutation

Answer 21

• a nucleic acid is replaced by another nucleic acid

- stop codons can be lethal

Question 22

Frame Shift Mutation

Answer 22

nucleic acids are inserted into the genome sequence (lethal)

Question 23

Phenylketonuna (PKU)

Answer 23

a molecular disease caused by the inability to produce the proper enzyme for the metabolism of phenylalanine

Question 24

Sickle-cell anemia

Answer 24

a disease in which red blood cells become crescent shaped b/c they contain defective hemoglobin

Question 25

Bacterialgenome

Answer 25

consists of a single circular chromosome located in the nucleic acid region of the cell

Question 26

Replication

Answer 26

begins at a unique origin of replication and proceeds in both directions simultaenously 5' to 3' direction

Question 27

Genetic Variance

Answer 27

-reproduce by binary fission (a sexual process)

Question 28

Transformation

Answer 28

the process by which a foreign chromosome fragment (plasmid) is incorporated into the bacterial chromosome via recombination

Question 29

Conjugation

Answer 29

- sexual mating in bacteria | - the transfer of genetic material between two bacteria that are temporarily joined

Question 30

Transduction

Answer 30

occurs when fragments of the bacterial chromosome become packaged into the viral progeny produced during such a viral infection (bacteriophages)

Question 31

Recombination

Answer 31

occurs when linked genes are spearated

Question 32

Transcription

Answer 32

based on the accessibility to control DNA polymerase, which is directed by an operon - includes an operon region and a promoter region

Question 33

Inducible systems

Answer 33

- the repressor binds to the operator, forming a barrier that prevents RNA polymerase from transcribing the structural genes - for transcription to occur, an inducer must bind to the repressor (inducer-repressor complex) - the inducer is usually the substrate

Question 34

Repressible Systems

Answer 34

- the repressor in inactive until it combines with the corepressor - corepressors are often end products of the biosynthetic pathways they control