Unit IV Recitation Quizzes and Learning Objectives

how many sets of histone molecules are in each nucleosome

8

first step of DNA replication

DNA primase initiate DNA replication; form RNA primers on both strands at a replication fork

series of DNA coiling

DNA wrapped around histone proteins (form nucleosome); nucleosome compacted into chromatin fibers; chromatin fibers coil into looped domains; looped domains compacte, forming chromosomes

transcription termination

RNA polymerase recognizes a termination sequence of bases; RNA polymerase separates from the template DNA; in Eukaryotic RNA polymerase adds 10-35 nucleotides to mRNA after it passes termination

fourth step of DNA synthesis

RNA primer is degraded and gaps filled in with other DNA polymerase; leaves a nick

DNA is duplicated during __________ of the cell cycle

S phase

what 3 molecules are involved in translation

mRNA, tRNA, and ribosomes

nontemplate strand

may not code for a protein

The correct number of chromosomes is maintained during sexual reproduction by

meiosis, which reduces the chromosome number by half

The mitotic spindle is made of:

microtubules

difference between mitosis and cytokinesis

mitosis is process in which cell information is duplicated and separation in two begins; cytokinesis is when cytoplasm divides

_________ are the building blocks of DNA

nucleotides

telophase I

one of each pair of homologous chromosomes is at each pole; cytokinesis occurs

During which phase does crossing-over occur

prophase I

Homologous chromosomes undergo synapsis during

prophase I

4 stages of M phase

prophase, metaphase, anaphase, telophase

Which of the following represents the overall sequence of events during mitosis?

prophase, metaphase, anaphase, telophase

translation initiation

small subunit binds to mRNA; initiator tRNA binds to start codon in mRNA (AUG); large ribosomal subunit bonds

In essentially all organisms, the AUG codon codes for:

the initiation of translation

transcription

the synthesis of RNA molecules complimentary to DNA

what base is different in DNA

thymine

A sequence of bases located upstream from a reference point occurs

towards the 5' end of the mRNA sequence

The final product of DNA replication is

two DNA molecules, each of which contains one new and one old DNA strand

Introns in pre-mRNA are known to:

undergo excision, whereby they are spliced out of the message

what base is different in RNA

uracil

template strand

used for transcription

plant cell cytokinesis

vesicles gather on midplane; small vesicles fuse together forming larger vesicles (eventually one large vesicle); new cell walls and new plasma membrane formed

can template and nontemplate strands switch with each different gene

yes

does more than one codon specify most amino acids

yes

Initiation of transcription requires:

a promoter sequence

kinetochore

a protein structure to which microtubules bind during mitosis

The 5' end of each Okazaki fragment begins with

a separate RNA primer

The 5' end of each Okazaki fragment begins with:

a separate RNA primer

During prophase I, each chiasma represents:

a site of crossing-over

The 3' end of eukaryotic pre-mRNAs are changed by:

adding 100−250 adenine nucleotides

translation elongation

adding amino acids to a growing polypeptide; hydrogen bonds formed between tRNA and mRNA; ribosome shifts one codon to the right

Uracil forms a complementary pair with __________ in RNA and __________ in DNA.

adenine; adenine

nonsense mutation

amino acid converted to a stop codon prematurely

Ribose differs from deoxyribose by having

an extra hydroxyl group

During which of the following stages of meiosis do the sister chromatids separate?

anaphase II

RNA polymerase

binds nucleotides to RNA

A site

binds the tRNA delivering the next amino acid

P site

binds the tRNA holding the growing chain

Single Strand Binding Protein (SSB)

binds to single strands of DNA and prevents the helix from reforming before it can be used as a template for replication

Topisomerase

breaks one or both DNA strands preventing excessive coiling during replication and rejoins them in a more relaxed configuration

which direction is RNA synthesized

5' to 3'

If a DNA template strand has a sequence of 3'TACAATGTAGCC5' then the RNA produced from it will be which sequence

5'AUGUUACAUCGG3'

start code

AUG

Which of the following adds new nucleotides to a growing DNA chain

DNA polymerase

second step of DNA replication

DNA polymerases extend the leading and lagging strand copies from the RNA primers in a 5' -> 3' direction

Which of the following is NOT a criterion for an organism's genetic material?

The genetic material must be dynamic, changing rapidly in response to changes in the environment

G2 function

cell growth, increased protein synthesis

G1 function

cell growth, normal metabolism, positive signals sends to S phase

mutagens

chemical and radiation

early prophase

chromosomes condense, spindles form, centrioles migrate to poles

telophase

chromosomes decondence, spindle disassemble, nuclear envelope forms, cleavage furrow begins forming

metaphase II

chromosomes line up along cell's midplane

chromosome

condensed DNA

What type of bond links nucleotides

covalent

significance of meiosis

creates genetic diversity

how is genetic diversity formed by meiosis

crossing-over and independent assortment; sexual reproduction

The sources of genetic variation during meiosis are

crossing-over and the random assortment of maternal and paternal chromosomes

cytokinesis

cytoplasmic division; cleavage furrow deepens as waistband tightens, pinches cells apart

DNA from any source contains about the same amount of guanine as __________

cytosine

Which purine base forms 3 hydrogen bonds when binding its complementary nucleotide

guanine

meiosis I

homologous chromosomes separate

anaphase I

homologous chromosomes separate and move to opposite poles; sister chromatids remain attached at their centromere

prophase I

homologous chromosomes synapse and exchange segments by crossing-over; nuclear envelope breaks down

release factor

hydrolysis bond between peptide chain and tRNA

3 stages of transcription

initiation, elongation, termination

The cell cycle of a typical somatic cell consists of ___________ and M phase

interphase

2 stages of cell cycle

interphase, M phase

splicing

involves snRNPs (small nuclear riboneucleoprotein complexes); RNA within intron may splice itself without enzyme

A replication fork

is a Y-shaped structure where both DNA strands are replicated simultaneously

If a cell is in G2:

it has twice the amount of DNA present in telophase

Eukaryotic chromosomes consist of

linear DNA molecules complexed with nucleosomes

The enzyme DNA ligase is responsible for:

linking short DNA segments

DNA ligase

links Okazaki fragments by joining the 3' end of the new DNA fragment to the 5' end of the adjoining DNA

transposons

movable sequences of DNA that "jump" into the middle of a gene, inactivate it

telophase II

nuclei form at opposite poles of each cell; cytokinesis occurs

late prophase

nucleolus disappears, nuclear envelope breaks down, chromosomes captured by spindle, chromosomes move towards midline

promotor

nucleotide sequence in DNA to which RNA polymerase and associated proteins initially bind

helicase

opens the double helix at replication forks by disrupting the hydrogen bonds that hold the two strands together

homologous chromosomes

paired chromosome, carry information about the same genetic trait, but not always the same information

dispersive replication

parent and new strands become randomly mixed

A ______ bond holds the amino acids of a growing polypeptide chain together during the elongation stage of translation

peptide

what type of bond joins amino acids to form proteins

peptide bonds

The nucleotides within DNA are composed of a:

phosphate group, deoxyribose sugar and nitrogenous base

Griffith

pneumococcus into mice; S strain (virulent) R strain (avirulent); living S cells, mice die; killed S cells mice live; living and killed R cells live; killed S + live R large portion die

nucleosome

positively charged histones associated with DNA (negative charge from photon groups) forming a protein core around which DNA winds

Watson & Crick

proposed model of DNA

ribosome subunits

protein and rRNA

missense mutation

protein function may be changed; one amino acid different

Which of the following is NOT a component of the translation machinery

protein polymerase

histones

proteins that facilitate chromosome packaging

Is adenine a purine or pyrimadine?

purine

mutational hot spots

regions of DNA more likely than others to undergo mutation

what sugar is RNA

ribose

molecular chaperones

ribosome-associated proteins help fold newly synthesized polypeptide chain into 3D shape

where is the site of translation

ribosomes

Avery, MacLeod, McCarty

separated S cells; separated S cells into lipids, proteins, polysaccharides, and nucleic acids; tested each part to see if it could transform R cells into S cells; lipids, polysaccharides, proteins did not cause transformation; nucleic acids were tranformed

meiosis II

separates chromatids

codon

sequence of 3 consecutive bases

triplet code

series of codons that specifies amino acid sequence

base substitution 3 types

silent, missense, nonsense

mRNA

single RNA strand that carries information for making a protein

tRNA

single RNA strand that folds back on itself to form a specific shape; transfers amino acid to ribosome

mitosis

single cell division which produces 2 daughter cells that are genetically identical

haploid

single set of chromosomes

anaphase II

sister chromatids separate, and chromosomes move to opposite poles

anaphase

sister chromatids separate, chromatids move towards respective poles, pulled by shortening of spindle

__________ contain identical DNA sequences and are held together by __________ during mitosis

sister chromatids; centromeres

chiasmata

sites of prior crossing-over

The information carried by DNA is incorporated in a code specified by the:

specific nucleotide sequence of the DNA molecule

metaphase

spindle microtubules line up chromosomes at cell's metaphase plate; each chromatid faces opposite pole, pushed along spindle

binary fission

splitting in two

translation termination

stop codon reached; protein release factor binds to mRNA; remaining parts of translation complex dissociate

rRNA

structural part of ribosome with catalytic function needed during protein synthesis

backbone of DNA

sugar-phosphate backbone

DNA primase

synthesizes short RNA primers on the lagging strand that begins replication of the leading strand

Which of the following contains the anti-codons used during translation?

tRNA

E site

tRNA that have delivered amino acids exit the ribosome

Meselson & Stahl

tested DNA replication; supported semiconservative replication

During prophase I of meiosis, homologous chromosomes lie side by side. This phenomeon is known as

tetrad formation

metaphase I

tetrads line up on cell's midplane; tetrads held together at chiasmata

Frameshift mutations result from:

the insertion or deletion of one or two base pairs

dimensions of DNA

0.34 nm, 3.4 nm, 2.0 nm

how many strands is RNA

1

sister chromatid

1 of 2 identical replicated chromosomes

how many chromatin are in a chromosome

2

how many strands is DNA

2

semiconservative replication

2 chains separate, each strand pairs with new complementary nucleotides to replace the missing pair

Which of the following best describes semiconservative replication

A DNA molecule consists of one parental strand and one new strand

fifth step of DNA synthesis

Okazaki fragments linked by a DNA ligase that repairs nick to form continuous strand

stop codes

UAA, UGA, UAG

conservative replication

2 parent strands remain together, 2 newly synthesized strands would form second double helix

transcription elongation

2 phosphate are removed from each nucleotide as they are added to the 3' end of the RNA; remaining phosphate becomes part of the sugar-phosphate backbone; last nucleotide has exposed 3' hydroxyl

diploid

2 sets of chromosomes

aminoacyl-tRNA synthetases

20 enzymes (1 for each amino acid); covalently links tRNA to amino acids

In a human cell at prophase I, there are __________ tetrads

23

How many nucleotides are contained in a single codon?

3

3', 5' phosphodiester linkage

3' carbon of one sugar is linked to 5' carbon of next sugar

structure of DNA

3' carbon of one sugar is linked to 5' carbon of next sugar

Which of the following nucleotide sequences represents the complement to the DNA strand 5' − AGATCCG- 3'?

3' − TCTAGGC- 5'

One of the mRNA codons specifying the amino acid leucine is 5'-CUA-3'. Its corresponding anticodon is

3'-GAU-5'

mRNA modification (post transcription)

5' cap (stabilizes and allows ribosomes to bind), poly-A tail at 3' end (exports mRNA from nucleus, stabilizes mRNA, initiation of translation)

Central Dogma

DNA codes for RNA, which codes for proteins

Which of the following causes the unwinding of the DNA double helix

DNA helicase

third step of DNA replication

DNA polymerase slides along; leading strand toward fork, lagging strand away from fork; Okazaki fragments are short segment of strand beginning with RNA primer

3 stages of interphase

G1, S, G2

What enzyme is responsible for the synthesis of mRNA

RNA polymerase

transcription initiation

RNA polymerase recognizes a promoter, unwinds the RNA double helix and initiates transcription

silent mutation

a change in a base that yields the same polypeptide sequence

DNA replication

a chromosome becomes duplicated so that it consists of two identical sister chromatids that later separate at anaphase; genetic material must be precisely duplicated and distributed to the daughter cells

centromere

a point of chromosome constriction that binds kinetochore proteins; links sister chromatids

To prevent disastrous consequences, the eukaryotic cell cycle is controlled by

a series of cell cycle checkpoints

Hershey & Chase

bacteria, 35S, 32P, viruses; S in protein, P in nucleic acid; S in supnatant (not injected into cell); P in pellet (injected into cell)

Watson-Crick model

because nucleotides pair with each other in complimentary fashion, each strand of the DNA molecule could serve as a template for synthesizing the opposite strand

small subunit

binding site for mRNA, initiation proteins

EPA site

binding sites for tRNA

Cytokinesis in plant cells begins with the formation of a(n)

cell plate

gametes

cells produced in meiosis; reproductive cells

significance of mitosis

cells receive identical chromosomes; growth and repair of body tissues

check points

check for proper coding before continuing in cell cycle

During prophase, __________ is(are) compacted into visible chromosomes

chromatin

prophase II

chromosomes condense again following brief period of interkinesis; DNA does not replicate again

S phase function

chromosomes replicate & histone synthesis

genetic code

codons for amino acids and for start and stop signals

scaffold protein

coiled chromatin attaches to larger nonhistone proteins

zygote

combination of 2 gametes (egg & sperm cell unite)

Hydrogen bonds can form between guanine and __________, and between adenine and __________.

cytosine; thymine

frameshift mutation

deletions or insertions

what sugar is DNA

deoxyribose

DNA components

deoxyribose (pentose sugar), phosphate, one of four nitrogenous bases

In an animal cell, a zygote (fertilized egg) contains the __________ complement of chromosomes

diploid

ploidy of zygote

diploid

meiosis

diploid cell undergoes genetic rearrangement and two successive nuclear divisions; resulting in 4 genetically different haploid daughter cells

introns

do not code; get removed

Nucleosomes are best described as

eukaryotic DNA associated with histone proteins

exons

expressed sequences that are parts of the protein-coding sequence

ploidy of gametes

haploid

what bonds hold together nitrogenous bases

hydrogen bonds

where does transcription occur

in the nucleus

where does translation occur

in the ribosomes

The RNA segments laid by DNA primase are responsible for

initiating DNA synthesis

Interrupted coding sequences include long sequences of bases that do not code for amino acids. These noncoding sequences, called __________, are found in __________ cells.

introns; only eukaryotic

In DNA replication, the lagging strand

is synthesized as a series of Okazaki fragments

The kinetochore serves which of the following functions

kinetochores attach to microtubules during mitosis

DNA polymerase

links nucleotide subunits to form a new DNA strand complementary to a DNA template

tRNA recognizes codons in the:

mRNA strand

DNA serves as the template for

mRNA, tRNA, and rRNA