LS 7A--Week 6: Protein Structure & Translation

Which of the following sequences of events correctly describes the progress of a protein that will be secreted from the cell? 1. SRP binds to the growing polypeptide chain and to the ribosome. 2. Translation resumes. 3. SRP binds to its receptor. 4. The signal sequence is cleaved. 5. Protein synthesis begins in the cytosol. 6. Translation pauses.

5 → 1 → 6 → 3 → 2 → 4

Assuming A-U and G-C pairing between the anticodon and the codon, what anticodon in tRNAMet would pair with the codon 5'-AUG-3'?

5'-CAU-3'

The interactions between amino acids are major factors in determining the shape of a protein. These interactions can be affected by the environment surrounding a protein. Which of the following would have an effect on the shape of a protein? whether the other molecules in the environment are predominantly hydrophilic or hydrophobic the concentrations of ions present in the environment All of the other answer options are correct. the pH of the environment the temperature of the environment

All of the other answer options are correct.

Which of the following occurs in the A site of the ribosome during translation?

An incoming charged tRNA binds to this site.

Which of the following occurs in the E site of the ribosome during translation?

An uncharged tRNA is ejected from this site as the ribosome slides to the next codon.

In a protein-coding region, a mutation that replaces a single nucleotide for another always changes the resulting amino acid.

False

Most proteins retain metabolic activity when denatured.

False

Protein families contain proteins with identical primary, secondary, and tertiary structures.

False

Which of the following occurs in the P site of the ribosome during translation?

The tRNA carrying the growing polypeptide moves to this site as the ribosome slides to the next codon.

Where are ribosomes found inside a cell?

both in the cytosol and attached to the rough endoplasmic reticulum

Which of the following actions would affect the secondary, but not primary, structure of a protein?

break the hydrogen bonds between amino acids

Proteins that prevent inappropriate folding of newly synthesized proteins are called:

chaperones.

Which of the following accurately describes the path traveled by a new protein as it is synthesized and released from the cell?

cytosol → ER → Golgi → vesicle → plasma membrane → external environment

The unfolding of a protein by heat or chemical treatment is referred to as:

denaturation.

A region of a polypeptide that folds in a particular way, relatively independently of the rest of the molecule, is a folding:

domain

The process of a vesicle fusing with the plasma membrane and depositing its contents into the extracellular space is referred to as:

exocytosis.

Which one of the following can contribute to a protein's tertiary structure?

hydrogen bonding van der Waal's forces All of the other answer options are correct. covalent bonding ionic bonding

Secondary structure is characterized by which one of the following types of interactions?

hydrogen bonding within the peptide backbone

When a charged tRNA is about to bind to the vacant A site of a ribosome, where is the growing polypeptide?

in the P site

Which of the following organelles could be considered recycling centers of eukaryotic cells?

lysosomes

Which of the following are processed in the Golgi apparatus? (Select all that apply.) enzymes required for the synthesis of phospholipids proteins that will be broken down by lysosomes mRNA molecules for the removal of introns integral membrane proteins of the plasma membrane proteins that are secreted from the cell

proteins that will be broken down by lysosomes integral membrane proteins of the plasma membrane proteins that are secreted from the cell

In a population of organisms, beneficial and harmful random mutations are retained or eliminated through the process of:

selection

Ribosomes in prokaryotes and eukaryotes are:

similar in structure and translate using the same genetic code.

Which of the following brings amino acids to the ribosome for use in translation?

tRNA

The fully folded structure of a functional protein composed of a single polypeptide chain is referred to as the _____ structure.

tertiary

Disorders of which organelle are often associated with defects in transport from compartment to compartment, resulting in poor sorting of protein components within the cell?

the Golgi apparatus

Binding sites for tRNA are located in:

the large ribosomal subunit.

A protein with an internal signal sequence is MOST likely to be located in:

the nucleus.

Two major types of protein secondary structures are referred to as:

α helix and β sheet.