Biology Chapters 4, 14, and 15

In translation where do initiation, elongation, and termination steps take place?

All three take place on the ribosome

The enzyme that catalyze the attachment of __ __ to tRNA molecules are known as aminoacyl-tRNA synthetases or activating enzymes:

Amino acids

One site where tRNA binds to the ribosome is the A site. This is also known as the __ site:

Aminoacyl

A charged tRNA is composed of the tRNA to which the following has been attached:

An amino acid

The density of the bacterial DNA following the first round of DNA replication in the Meselson-Stahl experiment can best be described as:

An intermediate between 14N and 15N

The enzyme activity responsible for making peptide bonds between amino acids is found on:

An rRNA located in the large subunit of the ribosome

For proteins that are targeted to the ER where is the signal sequence usually located?

At the beginning of the protein (first several amino acids added during translation)

In E. coli oriC is the site at which replication:

Begins

The continuously synthesized DNA strand is called the _ strand while the discontinuously synthesized strand is called the _strand.

Leading, lagging

DNA _ is an enzyme that joins to adjacent Okazaki fragments during the synthesis of the lagging DNA strand

Ligase

DNA replication in eukaryotic cells is complicated by the fact that eukaryotic cells have

Linear chromosomes

AUG serves as the start codon as well as, to encode for the amino acid:,

Methionine

Chloroplasts

Occur in plants and other eukaryotes that go through photosynthesis, contain chlorophyll and perform photosynthesis

Short fragments of DNA created on the lagging strand of DNA during replication are called

Okazaki fragments

Short fragments of DNA created on the lagging strand of DNA during replication are called:

Okazaki fragments

During the synthesis of the lagging DNA strand

Okazaki fragments are joined by the enzyme, DNA ligase

In a bacterial cell several genes can be clustered together and transcribed onto the same mRNA molecule. Such a cluster of genes is known as an:

Operon

This DNA enzyme covalently links nucleotides together:

Polymerase

Of the following list which 3 items are required for DNA replication?

Polymerase Template nucleotides

The enzyme DNA _ synthesizes the RNA primers required by DNA polymerases during replication:

Primase

The __ is the part of the replisome composed of primase helicase, and accesory proteins that prime the lagging strand:

Primosome

The ability of a polymerase to remain attached to a template is called _:

Processivity

The function of telomeres is to

Protect the ends of chromosomes

Identify the stage of transcription where the bacterial RNA polymerase binds to the promoter. After binding

RNA polymerase begins to unwind the DNA helix, Initiation

In translation termination stop codons are recognized by what type of proteins?

Release factors

The partial opening of a DNA helix to form two single strands is called:

Replication fork

Microfilaments (actin filaments)

Responsible for the formation of cellular extensions and for the contraction, or pinching of cells during division.

The prokaryotic translation initiation complex consists of:

Special initiator tRNA charged with N-formylmethionine Small ribosomal subunit mRNA strand

Nucleotides contain:

Sugar Phosphate group. Nitrogenous base

The DNA backbone is composed of:

Sugars Phosphate groups

An important technological advance that allowed scientists to dechipher the genetic code was the ability to:

Synthesize RNA molecules with defined sequences

Place the steps of lagging strand synthesis in the correct order:

Synthesize primers using primase Synthesize DNA Replace RNA primers with DNA Seal nicks in the DNA

Which of the following describes a type of duplication that occurs right next to the original region?

Tandem duplication

The end of a bacterial transcription unit is marked by a:

Terminator sequence

The three sites where RNA bind to the ribosome are which of the following?

The aminoacyl site The peptidyl site The exit site

During DNA replication how many strands of DNA are used as templates to synthesize new strands?

how many strands of DNA are used as templates to synthesize new strands? , 2 Strands

Which origins are more sequence-specific?

oriC

During DNA replication

the LEADING strand is synthesized continuously while the LAGGING strand is synthesized as small fragments that are connected to each other to form a continuous strand.

Regarding Meselson and Stahl's experiment, the primary difference between the proposed models of DNA replication was related to:

the primary difference between the proposed models of DNA replication was related to: , How the parental strands were incorporated into the daughter strands

How many forms of the RNA polymerase found in prokaryotes are there?

1

Each aminoacyl-tRNA synthetase present in a cell recognizes:

1 of the 20 common amino acids.

Two ways that lysosomes can be activated

1. Fusing with a food vesicle produced by phagocytosis 2. Fusing with an old organelle

Functions of actin filaments

1. Pinching of the cell during division 2. Muscle Movement 3. Enzyme and ribosome binding

Order the steps in the targeting of proteins to the ER, starting at the top

1. Ribosome begins synthesizing protein 2. Signal sequence on the protein is recognized by the SRP 3. The SRP/protein complex is recognized by a receptor on the ER 4. The ribosome is docked on the ER 5. As the protein is assembled, it passes through a channel in the docking complex and enters the ER lumen

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement. Also organizes the cell's activities by the actions of three types of fibers

Prokaryotes have:

A single RNA polymerase

The NA structure proposed by Watson and Crick involves:

A sugar phosphate backbone. Two grooves (major and minor). A helical structure

The two functional ends of tRNA are which of the following?

Acceptor stem Anticodon loop

The digestive enzymes in the lysosomes are optimally active at which of the following pH ranges?

Acidic

What structures are involved in cell movement?

Actin filaments Microtubules

Telomeres are related to:

Cellular aging

Different models for DNA replication included:

Conservative replicationSemiconservative replicationDispersive replication

Plasmodesmata

Cytoplasmic connections between the cell walls of plants

Once synthesis has begun

DNA can only be synthesized in this direction: , 5' to 3'

This polymerase uses its 5' to 3' exonuclease activity to remove primer segments and its 5' to 3' polymerase activity to replace them:

DNA polymerase 1

Which DNA polymerase does not seem to play a role in replication but is involved in the DNA repair process?

DNA polymerase 2

The small ribosomal subunit performs the __ function of the ribosome:

Decoding

Select the functions of the ribosome:

Decoding the transcribed message Forming peptide bonds

This mutation is the loss of a portion of a chromosome:

Deletion

An _ cuts DNA internally and an _ cuts at the ends of DNA:

Endonuclease, exonuclease

The model organism used by Meselson and Stahl was:

Escherichia coli

Which types of cells have more than one origin of replication?

Eukaryotes

Microtubules

Fibers of the cytoskeleton that are responsible for moving materials within the cell and organizing the cytoplasm

Cristae

Folds in the inner membrane of the mitochondria that increase the surface area of the inner membrane

Changes in the sequence of DNA that alter the reading frame of the genetic message

Frameshift mutations

In prokaryotes the two daughter molecules (each a double strand) produced at the end of replication are intertwined, similar to two links in a chain. What is the name of the enzyme that links the two daughter DNA molecules:,

Gyrase

In the Meselson-Stahl experiment, what was the expected composition of DNA molecules after two rounds of replication, if the semiconservative model was correct?

Half of the molecules would have 2 light strands and half would have a heavy and light strand

How did the organic chemist Khorana determine the final missing pieces of the genetic code in cell free systems?

He synthesized defined artificial RNA molecules and used the to make polypeptides in a cell-free system

The sliding clamp of a DNA polymerase:

Holds the polymerase to the DNA template

The topological state of DNA refers to:

How the DNA coils

Put the steps of prokaryotic DNA replication in order:

Initiation at OriC Replication proceeds bidirectionally Replication ends at terminus

Which of the following describes a change in a chromosome resulting from a reattachment of a chromosomal fragment to the original chromosome but in the reverse order?

Inversion

Gap junctions

Involves connexon proteins that create a pore to connect cells

What is the function of the elongation factor EF-Tu during translation?

It binds a charged tRNA and GTP and brings the next tRNA to the empty A-site.

Which of the following describe the structure and function of the acceptor stem of a tRNA?

It is found at the 3' end of the tRNA It acts as the attachments site for amino acids It always ends in CCA

Typically the ribosome uses which AUG codon it encounters in an mRNA as a signal to start translation?

The first

In prokaryotes how do translation and transcription occur?

They are coupled

Which of the following statements regarding the ability of ribosomes to proofread amino acids attached to tRNA is true?

They cannot verify that the correct amino acid is attached to the transfer RNA

What is the function of the promoter in a bacterial transcription unit?

To form a recognition and binding site for RNA polymerase

What is the function of the terminator in a transcriptional unit in bacteria?

To signal the end of transcription

What class of enzymes relieve torsional strain in DNA strands ahead of the replication fork?

Topoisomerases

What type of mutation occurs when a piece of a chromosome is broken off and joined to another chromosome?

Translocation

Identify all of the following that are components of the prokaryotic core RNA plymerase

Two identical alpha subunits One beta prime subunit One beta subunit

Identify the three stop codons of the genetic code:

UGA UAA UAG

In order to determine the density of DNA strands Meselson and Stahl used this technique so that DNA fragments would migrate to the area in the gradient where they had the same density:

Ultracentrifugation

Endosymbiosis

When a smaller cell lives in a larger cell

Franklin determined that the structure of DNA was helical based on:

X ray diffraction analysis

What enzyme breaks down hydrogen peroxide to harmless substances in peroxisomes?

catalase

Granum

contains a few to several dozen thylakoids in the mitochondria

The level of telomerase stays high in these cells

despite their age: , Lymphocytes

Which of the following is a mutation that changes the structure of the chromosome itself?

duplication

In eukaryotes translation can occur either in the cytoplasm or on the __ ER:

translation can occur either in the cytoplasm or on the __ ER:, Rough