Genetics

Question 1

The basic unit of heredity is the ___. They are composed of __ and are located on the ___

Answer 1

gene, DNA, chromosome

Question 2

Mendel postulated four principles of inheritance: first that genes exist in ___ forms referred to as ___. A gene controls a specific ___ in an organism. The organism has ___ alleles for each inherited trait, one inherited from each ___. The two alleles ___ during ___ resulting in gametes that carry only one allele for any given trait. If two alleles in an individual organism are different, only one will be __ ___, and the other will be ____

Answer 2

alternative, alleles, trait, 2, parent, segregate, meiosis, fully expressed, silent

Question 3

When only one trait is being studied in the mating

Answer 3

monohybrid cross

Question 4

The individuals being crossed are the __ or ___ generation and the progeny generations are the ___ or __ generations

Answer 4

parental, P, filial, F

Question 5

The hallmarks of mendelian inheritance are the ___ of the silent phenotype in the __ generation and its subsequent ___ in ___% of individuals in the __ generation

Answer 5

disappearance, F1, reappearance, 25, F2

Question 6

The idea that the inheritance of one trait is completely independent of any other

Answer 6

mendel’s law of independent assortment

Question 7

In modern, non mendelian genetics, genes on the same chromosome will __ __ unless __ __ occurs. This breaks the linkage of certain ___. Generally, the ___ the genes are on the chromosome, the more likely they are to be inherited together.

Answer 7

stay together, crossing over, patterns, closer

Question 8

Fruit flies are advantageous for genetic research because they ___ often with a short __ __, they reproduce in __ __, its chromosomes are __ and easily recognizable in size and shape, and they are only ___ pairs. Also ___ occur relatively frequently

Answer 8

reproduce, lief span, large numbers, large, 4, mutations

Question 9

When an a person heterozygous for an allele produces a phenotype that is an intermediate of the phenotypes of the homozygotes

Answer 9

incomplete dominance

Question 10

When multiple alleles exist for a given gene and more than one of them is dominant, leading to full dominance only with the recessive allele. When more than one dominant allele is present, both will be expressed at the same time without a blending of the phenotype

Answer 10

codominance

Question 11

The sex chromosomes pair during ___ and segregate during the first ___ ___. Since females can produce only gametes containing the __ chromosome, the gender of a zygote is determined by the __ ___ of the male gamete. If the sperm carries a ___ chromosome, the zygote will be male, if it carries an ___ chromosome, it will be female. For every mating, there is a ___% change that the zygote will be male or female

Answer 11

meiosis, meiotic division, X, genetic contribution, Y, X, 50

Question 12

Genes located on the X or Y chromosome are called ___. In humans, most sex-linked genes are located on the __ chromosome.

Answer 12

sex-linked, X

Question 13

In humans, women have two X chromosomes and men only have __. As a result, recessive genes carried on the X chromosome will produce the ___ ___ in men because no -_ __ is present to mask them. The recessive phenotype is therefore much ___ ___ found in men. Examples of sex-linked recessives in humans are the genes for ___ and _____.

Answer 13

1, recessive phenotypes, dominant allele, more frequently, hemophilia, colour-blindness

Question 14

Men with an ____ recessive trait ___ pass the trait to their male offspring. However, they will pass the gene to all of their ___. Unless the daughter also receives the gene from the ___ she will be a phenotypically normal carrier of the trait. Because all of the daughter’s male children will receive their only X chromosome from her, ___ of her sons will receive the recessive linked allele

Answer 14

X-linked, cannot, daughters, mother, half

Question 15

Sex-linked recessives generally affect only __, they cannot be passed from ___ to ____, and they can be passed from ___ to ___ via a daughter who is a carrier

Answer 15

men, father, son, grandfather, son

Question 16

Interactions between the genotype and the ___ such as ____ can result in different ____

Answer 16

environment, temperature, phenotypes

Question 17

Hereditary systems can exist outside of the ___. For example, DNA is found in ___ and other ___ ___. These cytoplasmic genes may interact with __ __ and are important in determining the characteristics of their ___. ___ ____ in many microorganisms is regulated by cytoplasmic DNA known as ___ that contain one or more genes. These can be passed from one ___ cell to another via ___

Answer 17

nucleus, mitochondria, cytoplasmic bodies, nuclear genes, organelles, drug resistance, plasmids, bacterial, transformation

Question 18

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

Answer 18

nondisjunction

Question 19

Nondisjunction can result in ____ or _____. __ ___ is caused by Trisomy of chromosome ___. Most nondisjunctions are ___ causing the embryo to spontaneously ___ early in the pregnancy. Nondisjunction of __ __ may also occur, resulting in individuals with extra or ___ copies of the X or Y chromosomes

Answer 19

monosomy, trisomy, down syndrome, 21, lethal, abort, sex chromosomes, missing

Question 20

Mutations in somatic cells can lead to ___. Mutations that occur in the gametes will be ___ __ to the offspring. Most mutations occur in regions of _____ ___, and are silent. Mutations that do change the sequence of amino acids in proteins are most often ___ and ____.

Answer 20

tumors, passed down, noncoding DNA, deleterious, recessive

Question 21

____ agents induce mutations. These include ___ rays, ___, ___ rays, and ___. It can also be chemical compounds such as ___ which inhibits __ ___, or ___ gas, which ____ guanine in DNA. These agents are sometimes also ___.

Answer 21

mutagenic, cosmic, x-rays, UV, radioactivity, colchicine, spindle formation, mustard, alkylates, carcinogenic

Question 22

In a gene mutation, ___ _ are added, deleted or ___ thus altering the amino acid sequence. This creates a -__ ___.

Answer 22

nitrogenous bases, substituted, mutated protein

Question 23

when a nucleic acid is replaced by another nucleic acid; generally involves 1-3 nucleotides

Answer 23

point mutation

Question 24

When a mutation results in the same amino acid and there is no change in the resulting protein

Answer 24

silent mutation

Question 25

When a mutation results in a different amino acid and there is a change in the resulting protein

Answer 25

missense mutation

Question 26

When a mutation results in a stop codon

Answer 26

nonsense mutation

Question 27

___ mutations are often lethal or severely inhibit the organism function. While the length of the ___ does not change with any of the mutations, the ___ __ of the proteins formed from an RNA sequence with this type of mutation could be much ___ due to the ___ stop

Answer 27

nonsense, genome, primary structure, shorter, premature

Question 28

When nucleic acids are deleted or inserted into the genome sequence; length of genome changes, is often lethal

Answer 28

frameshift mutation

Question 29

____ is a molecular disease caused by the inability to produce the enzyme for the metabolism of ____. A degradation product called __ __ accumulates as a result. These individuals are unable to consume products containing ____. ____ may result from impaired conversion of phenylalanine to tyrosine. It also results in _____, and __ ___. This disease is caused by a deficiency of ____ _____.

Answer 29

phenylketonuria, phenylalanine, pheylpyruvic acid, aspartame, hyperpneylanemia, phenylketonuria, mental retardation, phenylalanine hydrolase

Question 30

____ ___ is a disease in which red blood cells become __ shaped because they contain defective ___. The sickle-cell hemoglobin carry ____ ___. This disease is caused by a substitution of _____ for __ ____, because of a single base-pair substitution in the gene coding for hemoglobin. However patients do have less severe symptoms of ___ should they become infected

Answer 30

sickle-cell anemia, crescent, hemoglobin, less oxygen, valine, glutamic acid, malaria

Question 31

The bacterial genome consists of a single __ ___ located in the __ region of the cell. Many bacteria also contain smaller circular rings of DNA called ___, which contain __ ___. ___ are plasmids that are capable of integration in to the bacterial ___.

Answer 31

circular chromosome, nucleoid, plasmids, accessory genes, episomes, genome

Question 32

Replication of the bacterial chromosome begins at a unique ___, and proceeds in both directions ____. DNA is synthesized in the ___ direction

Answer 32

origin, simultaneously, 5’–>3’

Question 33

Bacterial cells reproduce by __ __ and proliferate very ___ under favorable conditions. Although binary fission is an ___ process, bacteria have ___ mechanisms for increases the genetic variance of a population

Answer 33

binary fission, rapdily, asexual, 3

Question 34

The process by which a foreign chromosome fragment is incorporated into the bacterial chromosome via recombination, creating new inheritable genetic combinations

Answer 34

transformation

Question 35

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

Answer 35

conjugation

Question 36

During conjugation, a -_ __ __ is formed between two bacterial cells, and genetic material is transferred from the donor __ ___ type to the recipient __. __ type. Only bacteria containing plasmids called __ __ are capable of this.

Answer 36

cytoplasmic conjugation bridge, male plus, female minus, sex factors

Question 37

The __ ___ is a sex factor in e coli. Bacteria possessing this plasmid are termed _____ cells, and those without it are called ___ cells. During conjugation, the ___ cell replicates its F factor and donates the copy to the ___, converting it to an F+ cell. Genes that code for other characteristics such as __ __, may be found on the plasmids and transferred into __ ___ along with these factors

Answer 37

F factor, F+, F-, F+ recipient, antibody resistance, recipient cells

Question 38

Sometimes the sex factor becomes ___ into the bacterial ___. During conjugation, the entire bacterial ____ replicates and begins to move from the donor cell into the recipient cell. The __ __ usually breaks before the entire chromosome is transferred, but the bacterial genes that enter the recipient cell can easily ___ with the genes already present to form novel __ ___. These bacteria are called ___ or __ ____ __ ____ cells.

Answer 38

integrated, genome, chromosome, conjugation bridge, recombine, genetic combinations, Hfr, high frequency of recombination

Question 39

a ____ is a virus that infects its host bacterium by attaching to the bacterium, boring a hole through the bacterial ___ ___ and injecting its __ ___ while its __ __ remains attached to the cell wall. Transduction occurs when fragments of the bacterial ___ become ___ into a -_ ___ produced during such a viral infection. These virons may infect other bacteria and introduce new __ __ through ____ with the new host cell’s DNA. The closer two genes are to one another on a ___, the more likely they will be transduce together. This fact allows ___ to map genes to a high degree of precision.

Answer 39

bacteriophage, cell wall, viral DNA, protein coat, DNA, packaged, viral progeny, genetic arrangements, recombination, chromosome, geneticists

Question 40

Recombination occurs when __ ___ are separated. It occurs by ___ and rearrangement of __ ___ of DNA when organisms carrying different genes or ____ for the same traits are ___.

Answer 40

linked genes, breakage, adjacent regions, alleles, crossed

Question 41

Regulation of transcription is based on the accessibility of __ ___ to the genes being transcribed, and is directed by an ____, which consists of ___ genes, an ____ region, and a ____ region on the DNA before the protein coding genes.

Answer 41

RNA polymerase, operon, structural, operator, promoter

Question 42

The sequence of nontranscribable DNA that is the repressor binding site

Answer 42

operator

Question 43

Noncoding sequence of DNA that serves as the inital binding site for RNA polymerase

Answer 43

promoter

Question 44

Gene that codes for the synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase from transcribing the structural genes

Answer 44

regulator gene

Question 45

RNA polymerase must also move past the ___ to transcribe the structural genes. ___ __ function by preventing or permitting the RNA polymerase to pass on to the structural genes.

Answer 45

operator, regulatory systems

Question 46

In an inducible system, the ___ binds to the operator, forming.a barrier that prevents RNA polymerase from ___ the structural genes. For transcription to occur, an ___ must bind to the repressor, forming an _____ ___. This cannot bind to the operator, thus removing it as a barrier permitting transcription. The proteins synthesized are thus said to be ____.

Answer 46

repressor, transcribing, inducer, inducer-repressor complex, inducible

Question 47

in inducible systems, the structural genes typically code for an ____, and the inducer is usually the ____, or a ____ of the substrate, upon which the enzyme normally acts. When the ___ is present, the enzymes are ____, when it is absent, enzyme synthesis is ___. In this manner, enzymes are transcribed only when they are actually ____.

Answer 47

enzyme, substrate, derivative, inducer, synthesized, negligible, needed

Question 48

In repressible systems, the repressor is ___ until is combines with the _____. These are often __ __ of the biosynthetic pathways they control. The proteins produced are usually ___ and are said to be ____, because they are normally being synthesized. Operons containing mutations such as ___ or whose __ ___ code for defective repressors are incapable of being _ ___. The resulting continuously synthesized enzymes are called ____

Answer 48

inactive, corepressor, end products, enzymes, repressible, deletions, regulator genes, turned off, constitutive