Bio Exam 2

Viruses

are smaller than cells

Most antibiotics are not effective against viruses because they ____ and this does not affect the activity of viruses.

inhibit synthesis of cell walls

The enzyme that HIV uses to transcribe viral RNA into DNA is

reverse transcriptase.

How many codons are in the mRNA sequence GGAAUGAAACAGGAACCC?

6

In DNA molecules,

cytosine pairs with guanine.

If one strand of DNA has the nitrogenous base sequence 5' ATTCGACGCTA 3', then the complementary strand has the nitrogenous base sequence

3' TAAGCTGCGAT 5'.

What type of RNA carries the information that specifies a protein?

messenger RNA

A three-base sequence (loop) in tRNA that is complementary to a three-base sequence in mRNA is

an anticodon.

In a "silent" mutation, the

codon that mutates does not cause a change in the amino acid specified.

What type of mutation occurred in the following?

Normal allele GGAAUGAAACAGGAACCC

Mutant allele GGAAUGAAACAGGUACCC

substitution

Consider the types of mutations and the circumstances in which mutations arise to select those TRUE statements below. (Select all that apply.)

Mutagens and meiosis are two sources of mutation.

A single-base insertion is usually more harmful than a single-base substitution.

Mutations can be useful to the organism.

What type of mutation occurred in the following?
Normal allele GGAAUGAAACAGGAACCC
Mutant allele GGAAUGAAAUCAGGAACCC

insertion

The influenza virus contains an RNA genome. Scientists typically need to make a new flu vaccine every year because

the virus can mutate into new strains.

The double helix of DNA is composed of building blocks called

nucleotides

Most viruses

infect only a few closely related species.

The DNA sequence 5' ATGCATGC 3' will pair with which of the following RNA strands?

3' UACGUACG 5'

In DNA molecules,

adenine pairs with thymine.

The DNA sequence 5' ATGCATGC 3' will pair with which of the following DNA strands?

3' TACGTACG 5'

Which of the following best describes the relationship between DNA, proteins, and RNA?

DNA is transcribed into RNA, then RNA is translated into proteins.

DNA differs from RNA because, unlike RNA,

DNA contains thymine.

In eukaryotic cells, sequences of mRNA removed before translation are called

introns

RNA differs from DNA in many ways, including

DNA contains deoxyribose while RNA contains ribose.

DNA contains thymine while RNA contains uracil.

DNA forms a double helix while RNA is usually single-stranded or forms loops.

RNA can catalyze some chemical reactions and DNA cannot.

The rungs of the DNA ladder are formed by base pairs

joined by hydrogen bonds.

What type of RNA carries amino acids to the ribosome?

transfer RNA

What process converts the mRNA "message" into a sequence of amino acids?

translation

In a "frameshift" mutation

the mutation is caused by an addition or deletion of one or more nucleotides.

Apoptosis is also called

programmed cell death.

DNA's sugar-phosphate backbones are joined with

covalent bonds.

When DNA replicates

one strand of the original DNA ends up in each of the new DNA molecules.

The first sign of cytokinesis in an animal cell is the formation of a

cleavage furrow.

The two main stages of the eukaryotic cell cycle are

interphase and mitosis.

Meiosis is a process used for

production of gametes.

In early stages of mitosis, a structure appears and functions to organize the protein subunits of the mitotic spindle. This is the

centrosome.

A discrete package of DNA and associated proteins in eukaryotes is a

chromosome.

Strands of DNA are joined by

hydrogen bonds.

All of the following refer to mitosis, except 

formation of gametes.

In an asexual life cycle, cells reproduce by

mitosis.

Mutations may be caused by

• errors in prokaryotic replication.

• errors in eukaryotic replication.

• exposure to chemicals.

exposure to radiation.

DNA and its associated proteins in the nucleus is referred to as the

chromatin.

The phase of mitosis in which the chromosomes condense and centrosomes move to opposite poles of the cell is

prophase.

The process by which a sperm cell combines with an egg cell is

fertilization.

The correct sequence for the phases of the eukaryotic cell cycle is

interphase—prophase—metaphase—anaphase—telophase—cytokinesis.

The phase of mitosis in which the chromosomes are aligned along the equator of the cell is

metaphase

Researchers exposed the microscopic roundworm, Caenorhabditis elegans, to disease causing bacteria. The roundworm can reproduce either asexually or sexually. In the presence of live bacteria, more roundworms reproduced sexually, and the resulting offspring were

unique, giving the roundworms a better chance of survival.

The human chromosomes that do not determine an individual's sex are

autosomes.

The chromosomal designation for a human male is

XY.

When chromosomes fail to separate during meiosis, this is known as

nondisjunction.

The Y chromosome

is smaller than the X chromosome.

Alternate forms of the same gene

are alleles.

The chromosomal designation for a human female is

XX.

When a diploid germ cell in a male goes through meiosis, it will generate

four haploid cells.

If you mate a donkey (2n = 62) with a horse (2n = 64) you get a mule. Mules are sterile and cannot produce gametes by meiosis because they

have an odd number of chromosomes.

Why is it essential that meiosis produce haploid cells?

to prevent the number of chromosomes from doubling each generation

Sexual reproduction includes

meiosis, fertilization, and mitosis.

If a diploid cell goes through mitosis it will generate

two diploid cells.

Human diploid cells have

23 pairs of chromosomes.

What is an advantage of sexual reproduction over asexual reproduction?

genetic variability during an ecological disaster

2n is an abbreviation for

diploid.

A diploid germ cell will produce cells with half the number of chromosomes, haploid cells, in 

meiosis.

Mitotic cell division creates identical copies by replicating a cell's DNA _________blank and then dividing _________

once; once

The process by which homologous chromosomes exchange genetic material

is crossing over.

One key reason why viruses are not considered living organisms is because viruses

do not reproduce on their own.

Our most potent weapon in the fight against viruses is

vaccinations.

In a sexual life cycle, a zygote (fertilized egg) grows to an adult by

mitosis

The phase of mitosis in which the centromeres split and sister chromatids are pulled to opposite poles of the cell is

anaphase

The process by which a sperm cell combines with an egg cell is

fertilization

The phase of mitosis in which the chromosomes condense and centrosomes move to opposite poles of the cell is

prophase

In meiosis, homologous chromosomes align next to one another during

prophase I.

Mendel's monohybrid cross of tall parents, each with the genotype Tt, resulted in a tall to short ratio of

3:1.

If the two alleles for a particular gene are different the gene pair is

heterozygous.

Homologous chromosomes have

the same genes but can have different alleles.

A portion of DNA that encodes a specific protein is a

gene

Phenotype refers to the

observable expression of the genes in an individual.

If the two alleles for a particular gene are identical the gene pair is

homozygous.

In pedigree charts, autosomal recessive conditions

may disappear in one generation and reappear in the next generation.

In humans, alleles for a gene locus on autosomes are inherited from

males and females (one allele from each parent).

If a diploid cell has 14 chromosomes, it will have

7 pairs of homologous chromosomes.

Mendel's monohybrid cross of tall parents, each with the genotype Tt, resulted in a tall to short ratio of

3:1.

Genotype refers to the

combination of alleles in an individual.

If you cross two heterozygous (Yy) pea plants, what proportion of the offspring will be heterozygous?

50%

A person has a recessive, faulty allele for a disease, but the person does not have the disease since they also have a normal dominant allele. This person

is termed a carrier.

An allele that exerts its effects whenever it is present is

dominant.

Average heights of American men and women have increased steadily since the 1940s. The best explanation for this observation is that height is

influenced by environmental changes like improvements in diet.

A pea plant with (Tt) as its genotype should be referred to as

heterozygous.

When Mendel crossed short (tt) pea plants with short (tt) pea plants the offspring

were all short.

The most common allele, genotype, or phenotype in a population is referred to as the

wild type.

Mutations produce new alleles that may

be beneficial to the organism's fitness

have no effect on the organism's fitness.

decrease the organism's fitness. 

increase diversity at a genetic locus. (all are correct)

Metaphase

Chromosomes align at equator of cell

Prophase

Chromosomes continue to condense and become visible

Telophase

Nuclear envelope forms

Interphase

DNA replicates

Cytokensis

The cytoplasm divides

Anaphase

Centromeres spli. Sister chromatids (now chromosomes) are pulled toward opposite ends of cell.

The genetic information in viruses

is either DNA or RNA.

An asexual process used by prokaryotes in which replicated DNA and other cell parts are distributed into two daughter cells is called

binary fission.

In eukaryotic organisms, the physical division of the cytoplasm of the parent cell into two individual daughter cells is called

cytokinesis

A zygote is

a diploid cell.

In the study of genetics, the offspring of the P generation are referred to as the

F1 generation.

When Mendel crossed tall (Tt) plants with tall (Tt) plants the offspring

were mostly tall individuals and a few short individuals.

Meiotic cell division replicates a cell's DNA _________and then divides ________.

once; twice