Cell Biology Homework Questions Exam 1

Example of fibrous protein

collagen

If you want to see the smallest detail on the outside of a cell, what is the best type of microscope to use?

scanning electron microscope

What is true of organelles?

-organelles can have different pH and other environmental features from the cytoplasm

-the nucleus is an organelle

-organelles are membrane bound compartments within cells

-organelles are found in all plant and animal cells

What is present in plant cells, but NOT in animal cells?

chloroplasts and central vacuole

Why are enzymes called catalysts of biochemical reactions?

Because they reduce the activation energy of a reaction

Match the amino acid with the group that best describes its R group

Thr  is

uncharged polar

Match the amino acid with the group that best describes its R group

Met is

uncharged nonpolar

Match the amino acid with the group that best describes its R group

Lys is

positively charged

An enzyme that breaks down nucleic acids is called a ___

nuclease

An enzyme that breaks down protein is called a ___

protease

Alpha-helices are found in MOST proteins. Which of the following is correct regarding the structure of alpha-helices?

The R groups face out/away from the center axis spanning the helix.

Which of the following statements about enzymes is NOT true?

Enzymes are irreversibly changed after a reaction and cannot be used again

Where does protein translation occur in prokaryotes?

on ribosomes in the cytoplasm

Where does protein translation occur in eukaryotes?

on free ribosomes in the cytoplasm and on ribosomes on the surface of the ER

Which of the following does NOT play a role in initiation of protein translation in eukaryotes?

a tRNA bound to the E site of the ribosome

Which of the following plays a role in the termination of protein translation?

binding of Release Factor to a stop codon in the A site of the ribosome

During the elongation stage of protein translation, where does a charged tRNA first bind in the ribosome? [NOT the first tRNA that binds during initiation]

The A site

A particular triplet of bases in the template strand of DNA is 5'-AGT-3'. The corresponding codon for the mRNA transcribed is

3’-UCA-5’

Which of the following statements best describes the termination of transcription in bacteria?

RNA polymerase transcribes through the terminator sequence, causing the polymerase to separate from the DNA and release the transcript.

In eukaryotes there are several different types of RNA polymerase. Which type is involved in transcription of mRNA known as pre-mRNA?

RNA polymerase II

What is the principal force that holds the two complementary strands together in a DNA molecule?

hydrogen bonds

The molecule shown below can be found in _______.

RNA

In the figure shown below, the arrow B points to:

a mRNA

What type of macromolecules help package DNA in eukaryotic chromosomes?

proteins