Bio

It is estimated that a human cell in G1 phase of the cell cycle contains 6 picograms of DNA in its nucleus. If you measure the DNA content at various stages of mitosis and meiosis, what amounts of DNA can be expected in the nuclei at the following stages? Prophase mitosis___; prophase I meiosis___; prophase II meiosis___; telophase mitosis___; telephase meiosis II___. (All amounts are in picograms)

12;12;6;6;3

You run a PCR reaction for five cycles starting with a single DNA duplex. Theoretically, how many copies of your sequence would you now have?

32

At the start of mitosis, how many sister chromatids are present in the human cell?

46

In human cells, at the end of mitosis and after cytokinesis, how many chromatids have moved into each daughter cell?

46

You want to amplify by PCR 450 base pairs of C. elegans gene cloned into plasmid. You designed primers 22 nucleotides in length that are complementary to the plasmid sequence immediately adjacent to both ends of the cloning site. What would be the exact size of the amplified fragment?

494

Why don't plant cells use a contractile ring to divide their daughter cells?

A contractile ring can't pinch a cell wall

cell cycle checkpoints:

All are correct

Based on the information shown in this image, which labeled strand is the leading strand?

D

Why are primers needed for DNA replication?

DNA polymerase can only add nucleotides to an existing chain.

Which statement is true regarding binary fission?

DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions.

Okazaki fragments are ligated to form a continuous DNA molecule after replication is completed.

False

True or false. Nondisjunction can only occur in the sex chromosomes and not the autosomes.

False

True or false. first-division nondisjunction will only yield gametes with an extra chromosome, whereas second-division nondisjunction will only yield gametes missing a chromosome.

False

First-division nondisjunction occurs when:

Homologous pairs fail to separate during anaphase 1

Meiosis _____ is sometimes called reductional division because _____.

I; the number of chromosomes is reduced by half

Meiosis _____ is similar to mitosis in that _____ separate.

II; sister chromatids

ATP, the ubiquitous molecule involved in providing energy for many cellular functions, is a nucleotide that includes ribose as its sugar component. ATP is also the monomer used when adding an A to the growing strand during DNA replication. How do these molecules differ?

In DNA replication, the ribose lacks a 2' hydroxyl group

Suppose a human patient is given a blood clotting factor produced in bacterial cells. I'm this example, the patient ___ a transgenic organism because ___.

Is not; the patient's genes are not modified

Suppose a human patient is given a blood clotting factor produced in bacterial cells. In this example, the patient __ a transgenic organism because __.

Is not; the patient's genes are not modified

A graduate student wants to create a recombinant DNA molecule and introduce this molecule into bacteria. What is the proper order of steps that he should follow?

choose plasmid/donor DNA → cut with restriction enzymes → join fragments via DNA ligase → transform bacteria

A protein that has a regular up-and-down pattern of abundance during the cell cycle and that triggers progress of the cell cycle by activating kinases is called a:

cyclin

A human cell with a total of 23 chromosomes is:

haploid

What is the name of the enzyme that separates the two strands of DNA during replication?

helicase

A DNA molecule is cut with two different restriction enzymes known to cleave it only once each. After gel electrophoresis, three different DNA fragments are detected. This result means that the original DNA molecule was:

linear

At which stage of the cell cycle could you see sister chromatids with a microscope?

m

A malignant cancer differs from a benign tumor in that:

malignant cancers invade surrounding tissue and benign cancers do not.

A eukaryotic chromosome has ___ origin(s) of replication, and a bacterial chromosome has ___ origin(s) of replication.

many, one

The assembly of what cytoskeletal structures are initiated by the M cyclin-CDK complex?

microtubules

Genes that promote cancer are called

oncogenes

Several years ago, a man noticed a small mole on his wrist. Years later, the mole grew in size and the man was diagnosed as having metastatic melanoma. This was likely the result of:

several mutations affecting proto-oncogenes and/or tumor suppressor genes.

In gel electrophoresis, DNA fragments are separated based on their:

size

Energy is required in order to add a nucleotide to the growing strand of DNA during replication. From where does that energy come?

the incoming nucleotide

During PCR, where does the energy come from that adds the nucleotide to the growing DNA strand?

the incoming nucleotides

The extra chromosomal DNA often found in bacteria is called a:

Plasmid

What type of gene is c-scr (cellular-src)

Proto-oncogene

Which of the answer options is not needed for DNA replication?

Ribosomes

Which statement represents a misconception about sister chromatids?

Sister chromatids are formed when the prokaryotic circular chromosome attaches at the plasma membrane.

What would happen to the daughter cells if the G2 phase of the parent cell is shortened?

The cells would be smaller than normal.

Suppose a research team does a detailed analysis of the DNA sequence of all three copies of chromosome 21 from an individual with trisomy 21 (Down syndrome). They discover that two of the three chromosomes are essentially identical in sequence, whereas the third chromosome has a significant number of sequence differences. Which of the answer choices is consistent with this observation?

The extra chromosome 21 resulted from second-division nondisjunction in one of the parents' gametes

The prokaryotic protein FtsZ is evolutionarily related to eukaryotic tubulin. What does that mean?

All of these

What would happen if a pair of sister chromatids only connected to the mitotic spindle at one of their kinetochores?

All of these are correct

Sexual reproduction results in an increase in genetic diversity because:

All of these choices are correct.

What feature is shared by restriction fragments produced by the restriction enzymes BcII and Mph1103? The downward arrow denotes the site of cleavage in each strand.

Both fragments have the same 4-base overhang, but one at the 5'- end and the other at the 3'-end.

Which of the answer options is true regarding DNA replication of a linear chromosome?

Both strands get shortened at opposite ends during replication.

Which restriction enzyme produces sticky ends? An arrow indicates the restriction site.

BssKI with the restriction sequence 5'-(down arrow)CCCGGG-3'

One method for changing the DNA sequence of a gene in its original location in the cell uses a type of technology known as:

CRISPR-Cas9

Recall the experiments of Rous and colleagues. If he had found that filtered cancer cell extract could not cause cancer when injected into healthy animals, what could he have deduced?

Cancer may be caused by bacteria. An intact cancer cell is necessary to cause cancer. A large protein may cause cancer.

Why would a compound that interferes with bacterial cell wall synthesis be useful for treating a bacterial infection?

It would limit growth of the bacterial population through cell division.

Imagine that a doctor is culturing cells from a malignant melanoma and from a normal skin sample. How would you expect these two cell populations to differ?

Malignant melanoma cells would have active telomerases that constantly replenish and lengthen telomeres.

Which of the answer choices is a characteristic of meiotic cell division?

Meiotic cell division results in halving the number of chromosomes.

Which statement regarding tumor suppressors are true?

Mutations affecting tumor suppressors can contribute to the development of cancers

Which of the statements is true regarding origins of replication?

None of the answer options is correct.

A researcher is evaluating the expression of p53 in cells she is culturing in the laboratory. She notices that in a small group of cells, high levels of phosphorylated p53 occur in the nuclei. What can she deduce about these cells?

These cells likely contain damaged DNA.

Why are the X and Y chromosomes not considered homologous?

They do not carry the same set of genes.

Why are telomeres a necessary component of linear chromosomes?

They maintain the length of a chromosome because DNA is shortened every time it is replicated.

A solution of DNA fragments of known sizes is sometimes placed in one of the wells during electrophoresis and used for size comparison.

True

True or false. Nondisjunction can occur in both mitosis and meiosis.

True

In mammals, females have two copies of the X chromosome, whereas males have only one copy. Dosage compensation (equalization of the numbers of each gene) is accomplished in mammals by:

females randomly inactivating one of the X chromosome in all cells.

Which of the choices is an example of a transgenic organism?

fish that "glow in the dark" by expressing fluorescent jellyfish proteins

Which of the answer choices is part of the process of binary fission in prokaryotes?

formation of a new cell wall