biol:1411 unit 2

lectures 15-28, chapters 7-11, & lab project 2

In terms of genetic diversity produced, what is the main difference between sexual and asexual reproduction?

Asexual reproduction produces offspring that are clones of one another (genetically identical). Sexual reproduction involves fusion of haploid gametes (produced by meiosis and are genetically variable), resulting in the offspring being highly variable genetically.

In single-celled organisms, reproduction and cell division are equivalent. However, this is not true in multicellular organisms. Why not?

In single-celled organisms, every cell division results in a new individual organism. In multicellular organisms, cell division is requires to generate many types of specialized somatic cells in the adult (these cells are not involved in reproduction). Relatively few cell divisions give rise to the cells that will undergo meiosis to product gametes for reproduction.

Describe the two events that characterize a sexual, or meiotic, life cycle

Meiosis is cell division in a diploid cell that produces haploid cells. Fertilization is the fusion of haploid gamete cells, resulting in a diploid zygote

What is Cell Division?

Reproduction of a cell to produce two new cells

What is Asymmetrical Cell Division?

Mother and daughter cells differ in size because the mother cell produces a daughter cell and remains unchanged

What is Symmetrical Cell Division?

Mother cell divides and produces two daughter cells that are identical and cannot be distinguished from one another

True or False: Single cell microbes are either symmetrical or asymmetrical

True

True or False: When cells are damaged or die, cell division of neighboring cells provides replacements

True

What is Asexual Reproduction?

Formation of new individuals without the union of genetic material from two different parents

How does Asexual Reproduction occur?

Budding or fragmentation

What happens if there are mutations in Asexual Reproduction?

The offspring and parent will not be genetically identical because the mutations with cause alterations in DNA, resulting in genetic variations

What is Binary Fission?

Asexual cell division that produces two genetically identical daughter cells from a parent cell

What is Mitosis?

Asexual cell division produces two genetically identical daughter cells

What kind of reproduction are Binary Fusion and Mitosis apart of?

Asexual Reproduction

What is Sexual Reproduction?

Gametes fuse to produce offspring that differ genetically from one another and the parents

What are Gametes?

Mature sexual reproductive cells (the egg or the sperm)

True or False: Sexual life cycle requires a type of cell division that doubles the amount of DNA carried in a cell

False. Sexual life cycle requires a type of cell division that HALVES amount of DNA carried in a cell

What would happen if cell division in a sexual life cycle did not half?

DNA would double with each cell fusionWaht

What is Meiosis?

Cell division that results in the production of daughter cells (gametes)

True or False: Meiosis decreases genetic diversity

False. Meiosis INCREASES genetic diversity

Meiosis only occurs in ___________.

Eukaryotes

What is a Somatic Cell?

All cells of the body EXCEPT germ cells and gametes

What is a Diploid?

Each contain two PAIRED sets of chromosomes

What are Homologous Pairs?

Tow matching chromosomes (one from each parent) that make a complete set in a diploid organism

Two chromosomes in a homologous pair are ____________ of each other

Homologs

True or False: Gametes have homologs

False. Gametes do not have homologs because they only contain a SINGLE SET of chromosomes

True or False: Gametes are haploid

True

What is Haploid?

Having a chromosome complement consisting of just one copy of each chromosome

Two haploid gametes fuse to form a ____________.

Diploid zygote

What is a Zygote?

Fertilized egg (created by the union of two gametes, when the gamete nuclei are fused)

What is Fertilization?

Union of gametes

What is Haplo-diplontic?

Life cycle in which the organisms spends significant time in both the haploid and diploid stages

What is the essence of sexual reproduction?

Random selection of one of the two homologs of each chromosome pari of the diploid

What causes a sexual life cycle to be haplontic, diplontic, or haplo-diplontic?

The time spent in haploid versus diploid stages

The molecules that make up a chromosome are ________ and ________.

a. dna; rna

b. nucleotides; nucleosides

c. proteins; phospholipids

d. dna; proteins

e. proteins; lipids

d. dna; proteins

The major drawback of asexual reproduction is that it

a. produces less variation among offspring compared to sexual reproduction

b. takes a great deal of time

c. generates variation

d. requires cell division

e. results in frequent replication errors (mutations

a. produces less variation among offspring compared to sexual reproduction

In sexually reproducing organisms, the diploid phase of the life cycle begins at

a. fertilization

b. spore formation

c. meiosis

d. gamete formation

e. mitosis

a. fertilization

During prokaryotic cell division, duplicated chromosomes separate from each other and are distributed into the daughter cells by

a. a mitotic spindle

b. attaching themselves to microtubules

c. the attaching of ter to a protein filament

d. repellent forces

e. the attaching of adjacent regions of ori to a protein filament

e. the attaching of adjacent regions of ori to a protein filament

After dna replication, each chromosome has ________ molecules of dna called ________, that after separation are known as _______ chromosomes

a. two; unreplicated chromosomes; sister

b. four; sister chromosomes; unreplicated

c. four; sister chromatid; unreplicated

d. two; sister chromatids; unreplicated

e. two; unreplicated chromosomes sister

d. two; sister chromatids; unreplicated

Which letter(s) indicate(s) a pari of homologous chromosomes?

a and b, c and d

A typical eukaryotic cell cycle consists of

a. mitosis and fertilization

b. prophase, metaphase, anaphase, and telophase

c. G1, the S phase, and G2

d. interphase, mitosis, and cytokinesis

e. mitosis and meiosis

d. interphase, mitosis, and cytokinesis

A cell with six pairs of chromosomes (2n = 12) begins meiosis. After meiosis I, each of the daughter cells will have

a. 6 chromosomes, each consisting of a single chromatid

b. 6 chromosomes, each consisting of two sister chromatids

c. 3 chromosomes, each consisting of two sister chromatids

d. 12 chromosomes, each consisting of a single chromatid

b. 6 chromosomes, each consisting of two sister chromatids

In an organism with a diploid number of 8, a gamete has ____ chromosomes and a liver cell has _____ chromosomes

a. 2; 8

b. 4;4

c. 4;8

d. 8;8

e. 8;4

c. 4;8

A cell undergoing meiosis has four pairs of homologous chromosomes. How many different combinations of maternal and paternal chromosomes are possible within the daughter cells that form?

a. 2

b. 4

c. 8

d. 16

d. 16 because 2^4

Which statement about aneuploidy is true?

a. It is a form of polyploidy

b. Aneuploidy results when a piece of one chromosome breaks off and attaches to another chromosome

c. It is almost nonexistent among human fertilized eggs

d. All trisomies in humans are a lethal condition causing death in the embryonic stage

e. An individual with an extra chromosome is trisomic

e. An individual with an extra chromosome is trimonic

Very few chromosome abnormalities (trisomies and monosomies) are observed in the human population because

a. most of these abnormalities lead to characteristics that are hard to recognize

b. they are all lethal in early childhood

c. meiosis distributes chromosomes to daughter cells with great precision

d. they are usually lethal and often cause spontaneous abortion of the embryo

e. the human meiotic spindle is self-correcting

d. they are usually lethal and often cause spontaneous abortion of the embryo

_____________ is an indicator of programmed cell death.

a. swelling of the membrane

b. loss of transcription control

c. cell lysis

d. the release of cell contents

e. fragmented chromatin

e. fragmented chromatin

Caspases play a role in the process of

a. trisomy

b. hexaploidy

c. nondisjunction

d. programmed cell death

e. aneuploidy

d. programmed cell death

Which is the correct order of changes in chromosomes during mitosis

a. replication → condensation → decondensation → separation

b. decondensation → separation → condensation → replication

c. replication → condensation → separation → decondensation

d. condensation → separation → replication → decondensation

c. replication → condensation → separation → decondensation

How does meiosis I differ from mitosis?

a. chromosomes are not replicated at the beginning of meiosis I as they are at the beginning of mitosis

b. centrosomes and mitotic spindles are not involved in chromosome movement during meiosis I as they are in mitosis

c. four daughter cells result from meiosis I, whereas only two daughter cells result from mitosis

d. homologous pairs of chromosomes are randomly divided into daughter cells during meiosis I but are both transmitted to daughter cells during mitosis

d. homologous pairs of chromosomes are randomly divided into daughter cells during meiosis I but are both transmitted to daughte cells during mitosis

How are the process of binary fission and the mitotic cell cycle similar?

Chromosome (DNA) replication produces identical daughter molecules (for every DNA molecule), which are then segregated into two daughter cells

The cytoskeleton plays an active role in two major process in cell division in both bacterial binary fission and M phase of the eukaryotic cell cycle. Briefly outline the role of the cytoskeleton.

The cytoskeleton is critical for movement of chromosomes to opposite ends of the cell and separation of the cells during cytokinesis

Haploid cells are those that have a single copy of each chromosome - there are no homologs present. Can a haploid cell undergo mitosis? Explain your answer with respect to events that occur at metaphase.

Yes. Homologs do not interact in mitosis - they align as individual replicated chromosomes on the metaphase plate. Thus whether a chromosome has a homolog in the cell or not has no effect on how it behaves during mitosis

If the two strains of true-breeding plants that have different alleles for a certain character are crossed, their progeny are called

a. F₁ crosses

b. the F₁ generation

c. the P generation

d. the F₂ generation

e. F₂ progeny

b. the F₁ generation

The genotype of an organism that expresses a dominant trait can be determined by

a. observing the genotype of the progeny from any cross

b. crossing the organism with a heterozygous dominant organism

c. crossing the organism with a homozygous recessive organism

d. observing the phenotype of the progeny from any cross

e. crossing the organism with a homozygous dominant organism

c. crossing the organism with a homozygous recessive organism

In a species of mince, short hair is dominant to long hair. If a short-haired individual is crossed with a long-haired individual and both long- and short-haired offspring result, one can conclude that

a. the long-haired individual is heterozygous

b. the short-haired individiual is heterozygous

c. this cannot be ansered without more information

d. the short-haired individual is homozygous

e. both individuals are homozygous

b. the short-haired individual is heterozygous

Cleft chin is an X-linked dominant trait. Assume that a man with a cleft chin marries a woman with a round chin. What percent of their male progeny will show the cleft chin trait?

a. 50%

b. 0%

c. 25%

d. 100%

e. 75%

b. 0%

In many animals, including humans, sex is determined by a single _______, or by a pair of them. Both male and females have two copies of each of the rest of the chromosomes, which are called _________.

a. sex chromosome; autosomes

b. allele; genes

c. autosome; sex chromosomes

d. gene; sex chromosomes

e. gene; autosomes

a. sex chromosome; autosomes

Genetic mutations are NOT

a. the process by which alleles can change to become different alleles

b. always deleterious

c. inherited changes in DNA

d. rare

e. stable

b. always deleterious

In a species of wild lupine flower, the smooth seed allele (S) is completely dominant over the wrinkled seed allele (s). If the alleles for height are incompletely dominant, such that TT is tall, Tt is intermediate, and tt is short, what will result from crossing a smooth-seeded short (SStt) plant with a wrinkled-seeded tall (ssTT) plant?

a. All the progeny will be smooth-seeded; one-half will be tall, and one-half will be short

b. All the progeny will be smooth-seeded and intermediate in heigh

c. All the progeny will be smooth-seeded and tall

d. All the progeny will be smooth-seeded and short

e. One-half of the progeny will be smooth-seeded and intermediate in height; one-half will be smooth-seeded and tall

b. All the progeny will be smooth-seeded and intermediate in height

A woman of blood group A has a child with a man of blood group B. The child’s blood type is O. What are the genotypes of the parents?

a. Mother: I^A I^O ; father: I^B I^b

b. Mother: I^A I^B ; father: I^B I^O

c. It is impossible for these individuals to have a child with type O blood

d. Mother: I^A I^A ; father: I^B I^a

e. Mother: I^A I^O ; father: I^B I^O

e. Mother: I^A I^O ; father: I^B I^O

The gene for body color and wing shape reside on the same chromosome in fruit flies. After crossing female flies having gray bodies and normal wings with male flies having black bodies and vestigial wings, Morgan observed that some of the F₁ flies had non-parental phenotypes (gray bodies with vestigial wings, or black bodies with normal wings). What accounts for this?

a. The alleles underwent independent assortment during meiosis

b. A certain percentage of the F₁ generation was affected by genetic mutations

c. The alleles for wing shape and body color recombined by crossing over

d. some flies with those phenotypes accidentally contaminated the cross

c. The alleles for wing shape and body color recombined by crossing over

DNA is held together in a double helix by the force of

a. ionic bonds

b. covalent bonds

c. ionic interactions

d. the twist

e. hydrogen bonds

e. hydrogen bonds

A-T base pairs in a DNA double helix

a. are chemically distinct from G-C base pairs

b. form three hydrogen bonds with each other

c. are of a different length than G-C base pairs

d. are more heat stable than G-C base pairs

e. are not accessible to DNA binding proteins

a. are chemically distint from G-C base pairs

If 30 percent of the bases in a double-stranded DNA molecule are T, ______ percent must be G

a. 50

b. 60

c. 40

d. 20

e. 30

d. 20

Which is the correct order of function (from first to last) of the enzymes listed?

a. Primase, DNA helicase, DNA polymerase, DNA ligase

b. DNA ligase, DNA polymerase, primase, DNA helicase

c. DNA helicase, primase, DNA polymerase, DNA ligase

d. DNA helicase, DNA polymerase, primase, DNA ligase

c. DNA helicase, primase, DNA polymerase, DNA ligase

In most cells, DNA replication

a. begins with unwinding of the DNA molecule at one or more specific locations and proceeds in only one direction

b. requires complete unwinding of the two strands of the DNA molecule before it can begin

c. is initiated from a single origin of replication at the middle of the chromosome

d. begins with unwinding of the DNA molecule at one or more specific locations and proceeds in both directions from that location

d. begins with unwinding of the DNA molecule at one or more specific locations and proceeds in both directions from that location

Refer to the figure showing a single replication fork. Which letter in the diagram identifies where the next Okazaki fragment will be started?

a. Letter C, at the 5’ end

b. Letter B, at the 5’ end

c. Letter E, at the 3’ end

d. None of the above

d. None of the above

Chronic myelogenous leukemia (CML), a type of blood-cell cancer, usually results from a chromosomal abberation whereby a segment of chromosomal DNA containing the gene ABL is inserted within the gene BCR. This creates a chimeric protein named BCR-ABL whose growth-promoting activity cannot be regulated by the normal regulatory mechanisms within the cell. Chimeric proteins such as BCR-ABL can be created by a __________ mutation.

a. point

b. deamination

c. translocation

d. deletion

e. inversion

c. translocation

In multicellular organisms

a. somatic mutation are passed on to offspring produced by sexual reproduction

b. all mutations produce phenotypic changes

c. all mutations are point mutations

d. somatic mutations may be passed to daughter cells by mitosis

e. meiosis is not required for the transmission of germ line mutations to the next generation

d. somatic mutations may be passed to daughter cells by mitosis

Which aspect of the biology of viruses was crucial in enabling Hershey and Chase to use the experimental design descried in the tutorial for deducing the chemical nature of genetic material?

a. viruses can live for long periods of time in a dormant state

b. virus particles are not cellular in nature and do not contain nuclei

c. viruses infect specific hosts and use cell surface properties of hosts to locate their targets

d. viruses insert only part of their bodies through the host membrane during infection

d. viruses insert only part of their bodies through the host membrane during infection

If the conservative model had been correct, how many generations of bacterial cell division would have had to pass before Meselson and Stahl would have observed evidence of a band in the CsCl gradient corresponding to a hybrid DNA molecule containing both ¹⁴N and ¹⁵N?

a. More than 10 generations

b. No generations; a hybrid would never form

c. 4 generations

d. 1 generation

b. No generations; a hybrid would never form

Which is a reason that explains why DNA replication occurs in a continuous fashion on one parental DNA strand and a discontinuous fashion on the other parental DNA strand?

a. Initiation of a new DNA strand requires the use of a primer

b. DNA replication depends on base pairings between a template and nucleotides being added to the new strand

c. A polymerase enzyme is needed to ensure that the replication process is both accurate and rapid

d. DNA polymerase only works to add nucleotides in one direction of the growing chain

d. DNA polymerase only works to add nucleotides in one direction of the growing chain

The first step in eukaryotic gene expression is

a. pre-nRNA is processed to make mRNA

b. RNA strands are combined to form DNA

c. mRNA is transported to the cytoplasm

d. ribosomes translate the mRNA sequence to make proteins

e. DNA is used as a template to make pre-mRNA

e. DNA is used as a template to make pre-mRNA

The process by which information coded in the sequence of nucleotide bases in DNA is passed to a sequence of nucleotide bases in RNA is called

a. replication

b. transcription

c. translation

d. RNA processing

b. transcription

Which component of transcribed RNA in eukaryotes is present in the primary transcript but is removed before translation occurs?

a. 5’ cap

b. Intron

c. Exon

d. Poly A tail

e. Ribosome binding site

b. Intron

Transcription in prokaryotic cells

a. is initiated at a promoter and uses only one strand of DNA (the template strand) to synthesize a complementary RNA strand

b. is terminated at a stop codon

c. does not need a promotor

d. is initiated at a start codon with the help of initiation factors and the small subunit of the ribosome

e. occurs in the nucleus, whereas translation occurs in the cytoplasm

a. is initiated at a promoter and uses only one strand of DNA (the template strand) to synthesize a complementary RNA strand

Which event must occur before eukaryotic mRNA is transcribed?

a. Capping of the 5’ end

b. Transport to the cytosol

c. Splicing out of the introns

d. Addition of a poly A tail to the 3’ end

e. Binding of a transcription factor to the promotor

e. Binding of a transcription factor to the promotor

Which statement best illustrates the concept that the genetic code is degenerate?

a. The codon CAG could code for two different amino acids

b. The codons CUU and CCU code for different amino acids

c. In some protist, UAG encodes for glutamine rather than functioning as a stop codon

d. The codons CCU and CCC both code for the amino acid proline

e. In nearly all organisms, UUU codes for phenylalanine

d. The codons CCU and CCC both code for the amino acid proline

At the initiation complex of translation in eukaryotes, the

a. poly A tail of mRNA is directly involved

b. large ribosomal subunit binds to the complex before the methionine-charged tRNA

c. complex of mRNA and the large ribosomal subunit are formed

d. anticodon of tRNA charged with methionine binds to mRNA associated with the small ribosomal subunits

e. large ribosomal subunit binds to mRNA, causing the release of the small subunit

d. anticodon of tRNA charged with methionine binds to mRNA associated with the small ribosomal subunits

The addition of sugar residues to the protein after translation is called

a. exonuclease digestion

b. glycation

c. proteolysis

d. glycoslyation

e. phosphorylation

d. glycoslyation

Which statement summarizes the process of transcription in cells?

a. The base sequence in an RNA molecule is used as a code to direct the sequence of amino acids linked together to form a polypeptide

b. The base sequence n a segment of DNA corresponding to a gene is used a as code to direct the sequence of amino acids linked together to form a polypeptide

c. An exact copy of the base sequence in a segment of DNA corresponding to a gene is synthesized as a segment of RNA

d. The base sequence in a segment of DNA corresponding to a gene is used as a template to form the complementary sequence in a segment of RNA

d. The base sequence in a segment of DNA corresponding to a gene is used as a template to form the complementary sequence in a segment of RNA

A pre-mRNA molecule contains two exon-intron boundary sites that are equidistant from each other and from the ends of the pre-mRNA molecule. How will the size of the final mRNA product compare to its pre-mRNA precursor?

a. The final mRNA molecule will be two-thirds as long as it pre-mRNA precursor

b. The final mRNA molecule will be three-fourths as long as its. pre-mRNA precursor

c. The mRNA molecule will be one-half as long as its pre-mRNA precursor

d. The final mRNA molecule will be one-third as long as its pre-mRNA precursor

a. The final mRNA molecule will be two-thirds as long as it pre-mRNA precursor

A __________ recognizes stop codons present at the A site of the ribosome to terminate elongation of a growing polypeptide chain.

a. stop anticodon

b. small ribosomal subunit

c. release factor

d. tRNA molecule

c. release factor

Which level is not a potential point of regulation of gene expression?

a. The level of processing mRNA

b. The level of protein export

c. The level of translation

d. The level of mRNA stability

e. The level of transcription

b. The level of protein export

A(n) _________ operon is turned on unless not needed

a. inducible

b. constitutive

c. repressible

d. clustered

e. active

c. repressible

The three basic parts of an operon are the

promoter, the operator, and two or more structural genes

In the lac operon, the inducer is _______

a sugar

The binding of an enhancer

a. stimulates splicing of all mRNAs

b. increases the stability of a specific mRNA

c. stimulates transcription of all genes

d. stimulates transcription of a specific gene

e. stimulates splicing of a specific mRNA

d. stimulates transcription of a specific gene

In a vertebrate, the amount of B-globin production varies tremendously among different cell types. This is because different cell types have different

a. silencers

b. transcription factors

c. inducers

d. enhancers

e. promoters

b. transcription factors

How does epigenetic regulation differ from other forms of gene regulation?

a. It is easily reversible

b. It can regulate multiple genes at once

c. It can be inherited by somatic daughter cells

d. It forms a physical barrier to prevent transcription

e. It is the least energetically exprensive

c. It can be inherited by somatic daughter cells

Which of the following is an example of an epigenetic change?

a. Methylation of a cytosine

b. The mutation of a repressor binding site

c. The mutation of an activator binding site

d. The binding of a transcription factor to a sequence of DNA

e. A mutation that changes adenine to guanine

a. Methylation of a cytosine

Alternative splicing in humans is generally regulated by binding between

a. DNA and sugars

b. DNA and proteins

c. RNA and proteins

d. RNA and sugars

e. DNA and RNA

c. RNA and proteins

Refer to the table. In which order do these steps occur just before expression of a gene in a eukaryotic cell?

a. C → D → A → B

b. A → D → B → C

c. C → A → D → B

d. D → B → C → A

c. C → A → D → B

The RB gene is involved in retinoblastoma, a form of cancer. What would be the consequence of having on ly defective RB protein present in a cell?

a. The cell would function normally

b. The cell would divide without RB control at the Restriction Points

c. The cell would remain in G1 at the Restriction Point

d. The cell would initiate apoptosis

b. The cell would divide without RB control at the Restriction Points

Chromosome number is reduced during meiosis because the process includes

a. two cell divisions without any DNA replication

b. two cell divisions with DNA replication before each

c. two cell division in which half of the chromosomes are destroyed

d. a cell division in which homologous chromosomes are separated from each other

e. sister chromatids being separated in Meiosis I

d. a cell division in which homologous chromosomes are separated from each other

The number of chromosomes in a cell of Japanese rhinoceros beetle that has gone through meiosis is 10. How many chromosomes are in a somatic cell of the dung beetle?

a. 5

b. 10

c. 20

d. 30

e. 40

c. 20

How does Meiosis I differ from Mitosis?

a. Homologous pairs of chromosomes are randomly divided into daughter cells during Meiosis I but are both transmitted to daughter cells during mitosis

b. Chromosomes are not replicated at the beginning of Meiosis I as they are at the beginning of mitosis

c. Four daughter cells result from Meiosis I, whereas only two daughter cells result from mitosis

d. Centrosomes and spindles are not involved in chromosome movement during gMeiosis I as they are during mitosis

a. Homologous pairs of chromosomes are randomly divided into daughter cells during Meiosis I but are both transmitted to daughter cells during mitosis

Which type of metaphase could the set of chromosomes be from?

a. Mitotic Metaphase

b. Meiotic Metaphase I

c. Meiotic Metaphase II

d. Both A and B are possible

e. Both A and C are possible

e. Both A and C are possible

The illustrated aneuploid karyotype of a male Drosophila melanogaster was observed. In this case, the fly had two copies of the male-limited Y chromosome along with the X inherited from the mother (XYY). Did nondisjunction happen in Meiosis I or Meiosis II of the XY sire?

a. Meiosis I

b. Meiosis II

c. Can’t tell

b. Meiosis II