Mastering Biology #10

You can tell that this is an image of a DNA nucleotide and not an RNA nucleotide because you see a _____.

sugar with two, and not three, oxygen atoms (DNA nucleotides are composed of deoxyribose sugars, whereas RNA nucleotides are composed of ribose sugars)

An old DNA strand is used as a _____ for the assembly of a new DNA strand.

template (An old DNA strand is used as a template for the synthesis of a complementary new strand)

What is different concerning the DNA in bacterial cells as opposed to eukaryotic cells?

the amount of DNA present whether the DNA is housed in a nucleus or no whether the DNA is linear or circular

What is cytokinesis?

the division of the cytoplasm that occurs in conjunction with telophase, the last phase in mitosis.

What is binary fission?

the method used by bacteria to divide

If the cleavage furrow or cell plate shown in the figure formed nearer one pole of the dividing cell rather than at the midline, what would be the predicted result?

the resulting cells would be very different in size

The first step of bacterial replication is _____.

- DNA replication (The DNA must be copied in order to proceed)

In a nucleotide, the nitrogenous base is attached to the sugar's _____ carbon and the phosphate group is attached to the sugar's _____ carbon.

1' ... 5' (The nitrogenous base is attached to the sugar's 1' carbon and the phosphate group is attached to the sugar's 5' carbon)

A diploid organism whose somatic (nonsex) cells each contain 32 chromosomes produces gametes containing _____ chromosomes.

16

Normal human gametes carry _____ chromosomes.

23

If guanine makes up 10% of the bases in a DNA double helix, what percent of the bases is adenine?

40%

Nucleic acids are assembled in the _____ direction.

5' to 3' (New nucleotides are added to the 3' end of a growing polynucleotide)

Genes provide the information needed to produce _____ in the cell.

Enzymes (Genes produce proteins which can be enzymes)

RNA processing involves the addition of ________ to the ends of the RNA transcript.

Extra nucleotides (are added to both ends of the primary RNA transcript)

What type of infectious agent causes Creutzfeldt-Jakob disease in humans?

Prion

The centrosomes move away from each other and the nuclear envelope breaks up during which phase of mitosis?

Prophase (the first phase of mitosis, when the centrosomes begin moving toward opposite poles and the nuclear envelope breaks up)

This is an image of a(n) _____. The figure shows an organic molecule which consists of a nitrogenous base, a five-carbon sugar, and one phosphate group.

Nucleotides (are composed of a pentose sugar, a nitrogenous base, and a phosphate group)

The RNA segments spliced to one another during RNA processing are _____.

RNA polymerase (untwists a portion of the DNA double helix)

The synthesis of a new strand begins with the synthesis of a(n) _____.

RNA primer complementary to a preexisting DNA strand

________ is a stage of mitosis.

Telophase

The chromosomes arrive at the poles and nuclear envelopes form during which phase of mitosis?

Telophase (the final phase of mitosis, when the chromosomes have arrived at the poles and the nuclear envelopes of the two new cells form)

What name is given to this process? A cycle consisting of 3 steps. In the lower left is a single hydra, labeled 1. At the top is the single hydra with a small hydra budding off of it, labeled 2. In the lower right are two individual hydra, labeled 3. The cycle continues back to step 1.

asexual reproduction

Bacteria divide by a process called ____.

binary fission

The structure where sister chromatids are joined is called the ________.

centromere

The sister chromatids separate and begin moving toward opposite poles of the cell during which phase of mitosis?

Anaphase (Sister chromatids separate and start their migration toward opposite poles during anaphase)

What happens during interphase?

Chromosome duplication occurs.

At the end of the mitotic (M) phase, the cytoplasm divides in a process called _________________.

Cytokinesis

Nucleosomes are made of ________.

DNA and histone proteins

Chromatin consists of

DNA and protein

Which of these is a difference between a DNA and an RNA molecule?

DNA is double-stranded, whereas RNA is single-stranded

Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?

DNA polymerase can assemble DNA only in the 5' to 3' direction (Since DNA polymerase can assemble DNA only in the 3' to 5' direction, the new strand complementary to the 3' to 5' strand must be assembled in short 5' to 3' segments, which are later joined together by ligase)

Short segments of newly synthesized DNA are joined into a continuous strand by _____.

Ligase (joins DNA segments into a continuous strand)

The chromosomes line up in the center of the cell during which phase of mitosis?

Metaphase (occurs in the middle of mitosis, when the chromosomes line up in the middle of the cell)

What must happen before a cell can begin mitosis?

The chromosomes must be duplicated.

Gametes are produced by _____.

meiosis (Meiosis produces haploid gametes from a diploid parental cell.)

Evidence for the spiral nature of DNA came from ________.

X-ray crystallography studies

The backbone of DNA consists of ______.

a repeating sugar-phosphate-sugar-phosphate pattern

After replication

each new DNA double helix consist of one old strand and one new strand

After DNA replication is completed, _____.

each new DNA double helix consists of one old DNA strand and one new DNA strand (DNA replication is semiconservative)

Human viruses that have appeared suddenly or have only recently come to the attention of medical scientists are called __________.

emerging viruses (Emerging viruses arise for a variety of reasons, including mutation of existing viruses)

Once meiosis I is completed, cells are ____________.

haploid

The first step in the replication of DNA is catalyzed by _____.

helicase (The first step of DNA replication is unwinding the DNA double helix)

What type of chemical bond joins the bases of complementary DNA strands?

hydrogen

What are prions?

misfolded proteins that catalyze the misfolding and aggregation of additional proteins.

DNA and RNA are polymers composed of ________ monomers.

nucleotide

How many enzymes are typically produced from a single gene?

one

plant cell cytokinesis differs from animal cell cytokinesis because ________.

plant cells form a cell plate and animal cells do not

The type of cell division that produces two genetically identical daughter cells is important for all of the following functions EXCEPT ________.

production of sperm and eggs

The action of helicase creates _____.

replication forks and replication bubbles

Pyrimidines are

single ring structures

A duplicated chromosome consists of two ______.

sister chromatids

What is a replication fork?

the transition region between paired and unpaired DNA strands

You have grown Neurospora under a variety of conditions listed below. You are trying to find a wild-type variety. Neurospora growing on which of these media could possibly be of the wild type?

the wild-type Neurospora could grow in any of these conditions

Which of these nitrogenous bases is found in DNA but not in RNA?

thymine (DNA contains thymine; RNA does not)

Thymine and cytosine differ from adenine and guanine in that ________.

thymine and cytosine are single-ring structures, whereas adenine and guanine are double-ring structures

In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.

thymine, cytosine

In a DNA double helix, adenine pairs with ________ and guanine pairs with ________.

thymine... cytosine

The cells that result from the mitotic cell cycle can be described as ________.

two cells, each with the same amount of genetic material and the same genetic information