AP Bio Unit 6 Bell Ringers

List the three parts of an operon.

1) promoter 2) operator 3) gene

A DNA sample is analyzed and is found to contain 22% cytosine. What percent of adenine would you expect the DNA to have?

28% adenine, 28% thymine, 22% guanine, and 22% cytosine

In which direction does DNAP III move across the DNA?

3' - 5'

If a strand of DNA reads: 5' - ACT - 3' what would the complementary strand read?

3' - TGA - 5'

In which direction does RNA polymerase move across the DNA?

3' to 5'

What is the corresponding mRNA sequence after the DNA is transcribed of 3' - CAGCTA - 5'?

5' - GUCGAU - 3'

List and describe the modifications that must occur to eukaryotic pre-mRNA.

5' cap: a modified guanine cap is added to the 5' end Poly-A tail: a sequence of 50-250 adenine are added to the 3' end Splicing: introns are spliced out of the pre-mRNA and the exons are joined together

What is a frameshift mutation?

A frameshift mutation is when the reading frame shifts (i.e. nucleotide is deleted or added)

What causes translation to stop?

A stop codon

Identify the bottom strand of DNA, the top strand of DNA, the periodical stops in the unwinding of DNA, and the direct breaking of hydrogen bonds?

A) Lagging strand B) Leading strand C) Okazaki fragments D) Replication forks

Does the DNA loosen or tighten with acetylation? How does this affect gene expression?

Acetylation loosens DNA, this causes genes to be more accessible to RNA polymerase

How does the genetic code support common ancestry?

All life uses the same genetic code, which suggests a common ancestor

How does apoptosis play a role an important role in development?

Apoptosis allows for limbs/digits to form

How do microRNAs and small interfering RNAs affect gene expression?

Both can bind to mRNA and degrade it or block translation.

During translation, the protein folds, but some proteins need the assistance of ___ proteins to fold correctly.

Chaperone

mRNA nucleotides are read in groups of 3 called

Codons

Which model of DNA replication has parental strands with the offspring separated into parental strands and new strands?

Conservative because the original parent strands are still intact.

What nucleotides hold a purine and pyrimidine together with three hydrogen bonds?

Cytosine and guanine

What are three differences between DNA and RNA?

DNA - 1) double-stranded 2) deoxyribose 3) thymine RNA - 1) single-stranded 2) ribose 3) uracil

Fill in the blanks: ___ → Transcription → ___ → Translation → _______

DNA, RNA, Protein

The length of DNA fragments (base pairs) are the results of which scientific procedure?

Gel electrophoresis

A key is a molecule the is unzipping a DNA, what is the name of the enzyme?

Helicase

What type of bond holds nucleotides together?

Hydrogen bonds

How does pre-mRNA differ from mRNA?

In eukaryotes, pre-mRNA has not been modified yet

When does the first stage begin in translation?

Initiation begins when the small ribosomal subunit binds to the mRNA and the first tRNA binds to the start codon

A model that represents a process occurring in a cell of a particular organism. Which of the following correctly explains the process?

Initiation of transcription is occurring because a strand of RNA is being produced from a DNA template strand.

List the three stages of translation.

Initiation, elongation, and termination

A point mutation is located in the middle of a normal hemoglobin molecule. What type of mutation is that?

Missense

Differentiate between missense and nonsense mutation.

Missense: a change in results in a different amino acid Nonsense: change results in a stop codon

What does redundancy refer to, in terms of the genetic code?

Multiple codons can code for the same amino acids

A model of a process involving nucleic acids. Which of the following best explains what process is represented?

New DNA strands are being synthesized in the 5' to 3' direction from their DNA templates.

Which scientific procedure allows for the amplification of DNA?

PCR

What functional group defines the 5' end of DNA?

Phosphate group

Why is DNA negatively charged?

Phosphate groups

What is the backbone of DNA composed of?

Phosphate groups and five carbon sugars

What are the rings in a bacterial cell?

Plasmid

The replication is identical. Is this in a prokaryotic or eukaryotic cell? How do you know?

Prokaryotic because it's round

Replication in prokaryotes differs from replication in eukaryotes for which of these reasons?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many.

Is the nucleotide with a double rings an example of a purine or pyrimidine?

Purine

How does initiation differ between prokaryotes and eukaryotes?

RNA polymerase can bind directly to the DNA in prokaryotes, while in eukaryotes it needs the help of transcription factors

The experiments conducted by Meselson and Stahl supported which model of DNA replication?

Semi-conservative

Erwin Chargaff investigated the nucleotide composition of DNA. He analyzed DNA from various organisms and measured the relative amounts of adenine (A), guanine (G), cytosine (C), and thymine (T) present in the DNA of each organism. Percents of G and C's are identical as well as A and T. Which of the following statements best explains the data set?

Since the %A and the %T are approximately the same in each sample, adenine and thymine molecules must pair up in a double-stranded DNA molecule.

What molecules would hold the DNA open as the "key" moves?

Single stranded binding protein

Which stage of the cell cycle does DNA replication occur?

Synthesis phase

During transcription, only one DNA strand is transcribed. What is the strand called?

Template strand

What is meant by the description "antiparallel" regarding the strands that make up DNA?

The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

To which site in the large ribosomal subunit does the first tRNA go to?

The first goes to the P site, all else go to the A site

Antibiotics can be used to kill the specific pathogenic bacterium, Mycobacterium tuberculosis, that causes tuberculosis. The appearance of antibiotic-resistant strains has made it more difficult to cure M. tuberculosis infections. These antibiotic-resistant bacteria survive and pass on the genes to their offspring, making the resistant phenotype more common in the population. DNA analysis indicates that the genes for antibiotic resistance aren't normally present in bacterial chromosomal DNA. Which of the following statements best explains how the genes for antibiotic resistance can be transmitted between bacteria without the exchange of bacterial chromosomal DNA?

The genes for antibiotic resistance are located on a plasmid that can be passed to neighboring bacteria

Where does transcription occur in eukaryotes?

The nucleus

A model shows some relevant details of how a deoxynucleotide, in this case dTMP, is added to a growing strand of DNA. The features of this model provide evidence for which explanation of why all growing strands are synthesized in a 5' to 3' direction?

The phosphate group, attached to the 5' carbon of the dTMP, forms a covalent bond with the oxygen atom attached to the 3' carbon of the growing strand.

Define transcription.

The synthesis of RNA using information form the DNA

Molecular biologists are studying the processes of transcription and translation and have found that they are very similar in prokaryotes and eukaryotes. Based on the table, which of the following best predicts a key difference in prokaryotes and eukaryotes with regard to transcription and translation?

The two processes will occur simultaneously in prokaryotes but not eukaryotes

What does it mean that DNA strands are anti-parallel?

They run in opposite directions.

In an inducible operon, transcription is usually ___.

off

In a repressible operon, transcription is usually ___.

on

Chargaff's analysis of the relative base composition of DNA was significant because he was able to show that

the amount of A is always equivalent to T and C to G