Exam 1

theory of epigenesis

organism develops from fertilized egg through developmental events transforming egg into adult

theory of preformationism

fertilied egg contains a complete miniature adult

homunculus

a sperm containing a miniature adult

cell theory

(Schleiden and Schwann)- all organism are composed of cells derived from preexisting cells

spontaneous generation

creation of living organisms from nonliving components

chromosomes are copied and distributed so each daughter cell receives identical diploid set of chromosomes from parental cell

mitosis

associated with sex gamete or spore formation. cells receive one chromosome from each chromosome pair (n). reduces amount of genetic material by 1/2

meiosis

diploid (2n)

two representatives of each chromosome

haploid (n)

number of chromosomes in gametes after meiosis.

genes

They are the functional units of heredity. take part in the production of proteins through the processes of transcription and translation.

DNA

built of different nucleotides (A)-adenine, (G)-guanine, (T)-thymine, (C)-cytosine

RNA

single stranded. built of ribose and contains nitrogenous base with (A)-adenine, (G)-guanine, (U)-uracil, (C)-cytosine

template for protein synthesis. carry genetic information from gene to ribosome

mRNA

carry amino acids to ribosome for protein synthesis allowing amino acids to associate with nucleic acids

tRNA

transcription

formation of a complementary RNA molecule from information in DNA

chemical information in mRNA directs the construction of a chain of amino acids (polypeptide) which fold into a protein

translation

If a scientist changed a cell's ionic composition and complementarity between DNA strands could no longer occur, what would the scientist first detect?

DNA becomes single stranded

Once a protein is made, its biochemical or structural properties play a role in producing

phenotype

central dogma

DNA is a template for RNA, which in turn is used to synthesize proteins.

How many different proteins, each with a unique amino acid sequence, can be constructed with a length of 6 amino acids?

its 20 to the number raised because there are 20 standard amino acids and then add the number of the length of protein sequence provided

transgenic organism

an organism produced by biotechnology that involves the transfer of hereditary traits across species

restriction enzymes

used by bacteria to cut and inactivate the DNA of invading viruses, could be used to cut any organism’s’ DNA. a primary discovery to generate recombinant DNA molecules

proteomics

study of the set of proteins present in a cell under given conditions, and their functions and interactions.

CRISPR-Cas gene editing mechanism

has applications that could repair mutations that cause human diseases. has already been used to repair mutations

Frederick Griffith and transforming agent

died as a result of combined an extract from heat-killed smooth bacterial cells with live rough cells and injected into them

Why did Hershey and Chase use the isotopes ³² P and ³⁵P in their experiments?

32P labeled DNA only; 35S labeled protein only

What are the exceptions to the general rule that DNA is the genetic material in all organisms?

Some viruses contain a genetic material composed of RNA.

Is the accompanying figure DNA or RNA? ________ Is the arrow closest to the 5' or 3' end? ________ Spleen diesterase is an enzyme that breaks the covalent bond that connects the phosphate to the 5' carbon. Assume that the dinucleotide is digested with spleen diesterase. To which base and to which carbon on the sugar is the phosphate now attached, A or T?

DNA; 3' end; A,3'

the structure of DNA, the covalently arranged combination of a deoxyribose & a nitrogenous base. if a molecule is composed of a purine or pyrimidine base & a ribose or deoxyribose sugar

nucleoside

Considering the structure of double-stranded DNA, which kind(s) of bonds hold one complementary strand to the other?

hydrogen

Which type of bond links nucleotides in a single strand of DNA?

phosphodiester

In an analysis of the nucleotide composition of double-stranded DNA to see which bases are equivalent in concentration, which of the following would be true?

A + C = G + T

Which of the following clusters of terms accurately describes DNA as it is generally viewed to exist in prokaryotes and eukaryotes?

double-stranded, antiparallel, (A + T)/(C + G) = variable, (A + G)/(C+ T) = 1.0

Which of the following would represent a complete turn of a DNA double helix?

minor groove to minor groove

Assume that the molar percentage of thymine in a double-stranded DNA is 20. What is the molar percentage of cytosine?

30%

Assume that A + T/G + C equals 0.5 in one strand of DNA. What is the ratio of these bases in the complementary strand?

0.50

Adenosine is an example of a ___; whereas adenine is an example of a ___.

nucleoside; nitrogenous base

What is the complementary DNA sequence to 5' ATGCTTGACTG 3'?

5' CAGTCAAGCAT 3'

the most abundant type of RNA in a cell. structural components of ribosomes for protein synthesis during translation

rRNA

Organized by the centrioles, what structures are important in the movement of chromosomes during cell division?

spindle fibers

contains the genetic material that is responsible for maintaining hereditary information

chromatin

is the structure for the production of ribosomes

nucleolus

is the structure where various RNAs, enzymes, and other molecular species assemble the primary sequence of a protein

ribosome

is a cytoplasmic structure involved (through the formation of spindle fibers) in the migration of chromosomes during mitosis and meiosis of animal cells

centriole

serves as an attachment point for sister chromatids and a region where spindle fibers attach to chromosomes

centromere

In ___ chromosome, the centromere is located at the end.

telocentric

In ____ chromosome, the centromere is located close to the end

acrocentric

In ___ chromosome, the centromere is located between the middle and the end.

submetacentric

In ____ chromosome, the centromere is located in the middle

metacentric

cells withdraw from the continuous cell cycle and enter a "quiescent" phase nondividing but metabolically active state

G0

A cell in the G2 phase of the cell cycle ________.

contains twice as much DNA as in the G1 phase

Migration of chromosomes is made possible by the binding of the spindle to the ___.

kinetochore

The event referred to as disjunction of sister chromatids

anaphase

Which list of steps in the eukaryotic cell cycle is given in the correct order? (step order listed left to right)

. . . G1 - S - G2 - M - G1 . . .

Each of the following events occurs during mitosis except _______.

polar microtubules contract, pulling attached chromosomes toward the poles

Which of the following are the areas where chromatids intertwine during meiosis?

chiasma

A bivalent at prophase I contains ________ chromatids.

four

In an organism with 52 chromosomes, how many chromatids would be expected in each cell after the second meiotic division?

26

For the purposes of this question, assume that a G1 somatic cell nucleus in a female Myrmecia pilosula contains 2 picograms of DNA. How much DNA would be expected in a metaphase I cell of a female?

4 picograms

What is the outcome of synapsis, a significant event in meiosis?

side-by-side alignment of homologous chromosomes

Which of the following is true about the second meiotic division?

Sister chromatids disjoin and are pulled to opposite poles.

Which of the following statements about meiosis is true?

The chromosome number is reduced by one-half.

Separation of sister chromatids occurs _______.

at anaphase in mitosis and anaphase II in meiosis

the exchange of genetic material between chromatids. occurs during 1st meiotic prophase

crossing over

is the point-by-point pairing of homologous chromosomes during the prophase of meiosis I.

synapsis

is a structure formed by the synapsis of homologous chromosomes & is equal to haploid number

bivalent

area of crossing over between chromatids

chiasma

a duplicated synapsed homologous chromosome, which is composed of four chromatids.

tetrad

another name for sister chromatid

monad

Which of the following is not a source of genetic variation in meiosis?

polar body formation

There is about as much nuclear DNA in a primary spermatocyte as in ________ spermatids.

4

List, in order of appearance, all the cell types expected to be formed during spermatogenesis.

spermatogonia, primary spermatocyte, secondary spermatocyte, spermatid, spermatozoa

During the polymerization of nucleic acids, covalent bonds are formed between neighboring nucleotides. Which carbons are involved in such bonds?

C-3' and C-5'

process whereby one organism is genetically altered by exposure to DNA from another organism. Because DNA can carry heritable “traits” from one organism to another, it must be the genetic material

transformation

Contains nitrogenous base and pentose sugar. Molecule composed of purine or pyrimidine base and ribose or deoxyribose sugar.

nucleoside

Nucleoside with phosphate group added.

nucleotide

short chain consisting of 20 nucleotides.

oligonucleotides

which is true regarding the 4 DNA bases

adenine (A) is equal to thymine (T)

in the chargaff rule which is true

guanine (G) is equal to cytosine (C)

what type of bond is (A) & (T)

double bond

what bond is (G) & (C)

triple bond

has nucleotides linked with phosphate. sugar ribose replaced deoxyribose. uracil replaces thymine. can be single or double stranded

RNA

naked cell. contain only cell membrane as the outer boundary of the cell. when used, virus does not need to be intact for infection to occur

protoplast

process of infection by viral nucleic acid into bacterial cells. concluded that DNA serves as genetic material.

transfection

replication depends on what which is isolated from E.coli following normal infection

RNA replicase

RNA-containing virus. the RNA serves a template for synthesis of complementary molecule

retroviruses

building block of nucleic acid. consists of nitrogenous base (purine & pyrimidines), pentose sugar, & phosphate group

nucleotides

genetic material is present in long, circular DNA molecule that is compacted into an enclosed region. does not undergo extensive coiling

nucleoid

initial stage of cell cycle. replication of DNA of each chromosome. two phases G1 & G2.

interphase

(animal cells) migration of two pairs of centrioles to opposite ends of the cell. nuclear envelope breaks down. nucleolus disintegrates

prophase

protein that holds sister chromatids together

cohesin

prevents degradation of cohesin at centromere

shugoshin

centromeres split and sister chromatids separate (disjunction) into daughter chromosomes.

anaphase

final stage of mitosis with two sets of chromosomes (one at each pole).

telophase

important in telophase. the division of the cytoplasm. two new cells are produced

cytokinesis

master control molecules before the next stage of the cycle. if failed, cell division proceeds into tumor

cell-cycle checkpoints

diploid cell duplicates its genetic material. homologous chromosomes pair (synapsis)

meiosis prophase I

hold nonsister chromatids together

terminal chiasmata

½ of each tetrad (dyad) homologous chromosomes separate. at the end, number of dyads equal haploid number present at poles

anaphase I

reapperance of nuclear membrane around dyads. nucleus enters into short interphase period. chromosomes don’t replicate

telophase I