Molecular Cumulative Questions

Prokaryotic cells contain which of the following?

Ribosomes

3 multiple choice options

All amino acids are composed of an amino group, a carboxyl group, and what other component?

Side chain

3 multiple choice options

What principle underlies the process of particles spreading out during diffusion?

Brownian motion

3 multiple choice options

Which of the following correctly describes quaternary structure in proteins?

Multiple polypeptide chains binding together to form one functional protein

3 multiple choice options

Water can form hydrogen bonds due to:

Partial negative charge on the oxygen and partial positive charge on the hydrogen

3 multiple choice options

Which of the following cellular components are ONLY found in eukaryotes?

Golgi apparatus

3 multiple choice options

Lipids are used for what purposes?

Cell structures, hormonal signaling, storage of energy, and waterproofing

If a piece of double stranded DNA contains 20% adenine nucleotides, what percentage of DNA would be cytosines?

30%

Which intermolecular force holds together the 2 strands of a DNA double helix?

Hydrogen bonding

What role do kinases play in the cell?

Activation or inactivation of target proteins by phosphorylation

In the formation of human gametes, the end products of meiosis I are two cells containing:

23 chromosomes each

3 multiple choice options

Unicellular eukaryotes that reproduce asexually do so by which process?

Mitosis

3 multiple choice options

The M-phase cell cycle checkpoint ensures that:

Chromosomes are all connected to the spindle

3 multiple choice options

Anaphase II of meiosis is most similar to:

Anaphase of mitosis

3 multiple choice options

Human somatic cells (body cells) contain two versions of chromosome #17, called:

Homologous chromosomes

3 multiple choice options

A diploid animal is heterozygous for both the head shape (H) and the tail length (T) genes. Which of the following gamete genotypes can it produce?

Ht

3 multiple choice options

What role do phosphatases play in signal transduction pathways?

They inactivate protein kinases to turn off signal transduction

3 multiple choice options

Cyclic AMP (cAMP) is an important ____________ in cell signaling.

Second messenger

3 multiple choice options

Intracellular receptors differ from membrane protein receptors in which of the following ways?

Intracellular receptors bind ligands in the cytosol, not the extracellular space

3 multiple choice options

In a monohybrid cross - a cross between heterozygotes - the probability of obtaining homozygous dominant offspring is:

25%

3 multiple choice options

True or false: Nucleic acids are polymers of nucleotides, which in turn are composed of a sugar, a phosphate, and a nitrogenous base.

True

True or false: Allosteric effectors bind to enzymes in their active sites.

False. Allosteric effectors bind to the allosteric site of an enzyme. This site is distinct from the active site where the substrate binds

True or false: Hairpins in the structure of tRNAs allow for codon-anticodon pairing with mRNA.

True

True or false: In feedback inhibition, the first product of a biochemical pathway acts to inhibit a later step of the pathway.

False. In feedback inhibition, the final product of a biochemical pathway acts to inhibit an earlier step (typically the first enzyme) in the pathway.

True or false: DNA is double-stranded, while RNA is single-stranded.

False. DNA is double stranded, but RNA can be single OR double stranded.

True or false: The nitrogenous base shown as a double-ringed structure is a pyrimidine.

False. The nitrogenous base is a purine, due to the double-ringed structure.

True or false: The chemical group H2N is a carboxyl group.

False. The chemical group H2N is an amino group.

True or false: Polymers are synthesized using dehydration reactions, while they are broken down using hydrolysis reactions.

True.

True or false: Enzymes work by raising activation energy for a chemical reaction.

False. Enzymes work by lowering activation energy for a chemical reaction.

True or false: In meiosis, genetic variation is introduced during Prophase I and Metaphase II.

False. In meiosis, genetic variation is introduced during Prophase I and during Metaphase I.

True or false: Mitotic spindle fibers connect to protein complexes called kinetochores, which surround the centromere region of chromosomes.

True.

True or false: Bacterial cells divide using the process of binary fission.

True.

True or false: Mitosis in plant cells differs from that in animal cells because plant cells do not contain nuclei.

False. Mitosis in plant cells differs from that in animal cells because plant cells do not contain a cell wall.

True or false: Cyclins are degraded during S-phase and G2-phase and are synthesized during M phase.

False. True or false. Cyclins are synthesized during S-phase and G2-phase and are degraded during M phase.

True or false: During S-Phase, the DNA is tightly condensed into chromosomes.

False. During prophase, the DNA is tightly condensed into chromosomes.

True or false: Mendel's Law of Segregation describes the observation that the segregation of alleles for one trait does not influence the segregation of alleles for another trait.

False. Mendel's Law of Independent Assortment describes the observation that the segregation of alleles for one trait does not influence the segregation of alleles for another trait.

True or false: Recombination in Meiosis refers to the exchange of DNA between sister chromatids.

False. Recombination in Meiosis refers to the exchange of DNA between homologous chromosomes.

True or false: During G0-Phase, the cell is growing, synthesizing ATP, other nucleotides, and proteins and preparing for replication of DNA.

False. During G1-Phase, the cell is growing, synthesizing ATP, other nucleotides, and proteins and preparing for replication of DNA.

True or false: A cell that skips the G2 checkpoint could begin mitosis without replicating its DNA.

True.

Briefly describe the 3 different functions that proteins perform in cells. (1-2 sentences each)

Structural Support: Proteins help maintain cell shape and form structures like hair, skin, and muscles.

Catalysis: Some proteins, called enzymes, speed up chemical reactions in the cell.

Signaling: Proteins help cells communicate and control processes, like responding to hormones or other signals.

Explain two chemical differences in the components that make up DNA and RNA molecules. (1-3 sentences)

DNA contains deoxyribose, as well as adenine (A), thymine (T), guanine (G), and cytosine (C).

RNA contains ribose, as well as adenine (A), uracil (U), guanine (G), and cytosine (C).

Newly synthesized G protein-coupled receptors must be trafficked to the plasma membrane to perform their role in cellular signaling. Describe the entire path these membrane proteins would travel on their way to the plasma membrane, starting with their synthesis. Explain what might happen during each step. (3-5 sentences)

Newly synthesized G protein-coupled receptors (GPCRs) are made in the rough endoplasmic reticulum (RER), where ribosomes attach and translate the receptor protein into the ER membrane. In the ER, the protein undergoes folding and modifications like glycosylation. Next, the GPCR is packaged into a transport vesicle and sent to the Golgi apparatus, where it may receive additional modifications and be sorted for delivery. After processing in the Golgi, the receptor is packaged into another vesicle that travels to the plasma membrane. The vesicle fuses with the membrane, inserting the GPCR so it can perform its role in cellular signaling.

Many pharmaceutical agents work by inhibiting enzyme function. Contrast competitive and non-competitive inhibitors: where do they bind and how do they each perform their functions? (1-3 sentences)

Competitive inhibitors bind to the enzyme's active site, directly competing with the substrate and preventing it from binding. They work by temporarily blocking access to the active site, and their effect can be overcome by increasing substrate concentration. In contrast, non-competitive inhibitors bind to a different site (allosteric site) on the enzyme, causing a change in the enzyme's shape that reduces its activity; this inhibition cannot be reversed by adding more substrate.

In the example of a cheetah chasing an impala, the hormone epinephrine was secreted from the impala's adrenal glands in response to stress. Epinephrine acts as a first messenger and stimulates many target tissues. What is the name of the long range signaling method used in this process?

Endocrine

In a muscle cell, describe the signaling pathway that is triggered in response to the epinephrine signal. Explain the step-by-step processes for the entire signaling pathway in as much detail as possible, including the two major types of cellular response. (5-10 sentences)

The ligand binds with the receptor (transduction) activating a G-protein, which goes through a conformational change. Second messengers, such as cAMP, are released throughout the cytoplasm. They connect with kinases, which take the phosphate groups from the ATP, creating a phosphorylation cascade that results in the release of epinephrine, or in other cases, gene expression or apoptosis.

Explain how a single epinephrine molecule can create a massive cellular response.

A single epinephrine molecule can trigger a massive cellular response by activating a signaling cascade that amplifies the signal, producing many cAMP molecules, which activate protein kinase A and lead to a large-scale enzymatic response, such as glycogen breakdown.