Biology Key Concepts: Cells, Metabolism, Genetics, and Cell Signaling

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have a nucleus and various organelles.

What are the hydrophobic and hydrophilic areas in a phospholipid bilayer?

The hydrophobic areas are the fatty acid tails that repel water, while the hydrophilic areas are the phosphate heads that attract water.

What are biomolecules?

Biomolecules are organic molecules that are essential for life, including carbohydrates, proteins, lipids, and nucleic acids.

What is glycolysis?

Glycolysis is the metabolic pathway that converts glucose into pyruvate, producing ATP and NADH in the process.

Where does the TCA cycle occur?

The TCA cycle, also known as the Krebs cycle, occurs in the mitochondrial matrix of eukaryotic cells.

What is the purpose of the electron transport chain?

The electron transport chain generates ATP through oxidative phosphorylation by transferring electrons and pumping protons across the mitochondrial membrane.

What powers ATP synthase?

ATP synthase is powered by the flow of protons (H+) across the membrane, creating a proton gradient.

Where do light reactions occur in plant cells?

Light reactions occur in the thylakoid membranes of chloroplasts.

What is the Calvin cycle?

The Calvin cycle is a series of biochemical reactions in plants that convert carbon dioxide and other compounds into glucose, occurring in the stroma of chloroplasts.

What is the difference between mitosis and meiosis?

Mitosis results in two identical daughter cells for growth and repair, while meiosis produces four genetically diverse gametes for sexual reproduction.

What is a gene?

A gene is a segment of DNA that contains the instructions for synthesizing proteins.

How are genes, DNA, chromosomes, and proteins related?

Genes are segments of DNA that are organized into chromosomes, and they provide the instructions for making proteins.

What is the central dogma of biology?

The central dogma of biology describes the flow of genetic information from DNA to RNA to protein.

What is differential gene expression?

Differential gene expression is the process by which cells regulate the expression of genes to produce different proteins, influencing cell function and identity.

How do polar and non-polar molecules cross lipid bilayers?

Polar molecules typically require facilitated diffusion through protein channels, while non-polar molecules can pass through the lipid bilayer directly.

What is the role of signal reception in cell signaling?

Signal reception involves the binding of signaling molecules to receptors on the cell surface, initiating a cellular response.

What is the function of RNA polymerase?

RNA polymerase synthesizes RNA from a DNA template during transcription.

What are the inputs and outputs of glycolysis?

Inputs: glucose, 2 NAD+, 2 ATP; Outputs: 2 pyruvate, 2 NADH, 4 ATP (net gain of 2 ATP).

What are the inputs and outputs of the TCA cycle?

Inputs: acetyl-CoA, NAD+, FAD, ADP; Outputs: CO2, NADH, FADH2, ATP.

What are the inputs and outputs of light reactions?

Inputs: light energy, water, NADP+, ADP; Outputs: oxygen, ATP, NADPH.

What are the inputs and outputs of the Calvin cycle?

Inputs: CO2, ATP, NADPH; Outputs: glucose, ADP, NADP+.

What is a transmembrane protein?

A transmembrane protein spans the entire lipid bilayer and can facilitate the transport of substances across the membrane.

What is the role of phosphate groups in signaling pathways?

Phosphate groups can activate or deactivate proteins, acting as molecular switches in signaling pathways.

How do mutations in DNA affect proteins?

Mutations can change the amino acid sequence of proteins, potentially altering their function or stability.

What is the importance of genetic diversity?

Genetic diversity is crucial for the survival and evolution of species, allowing populations to adapt to changing environments.

Where do the carbon atoms in glucose come from?

The carbon atoms in glucose primarily come from carbon dioxide absorbed during photosynthesis.

What is the endomembrane system?

The endomembrane system is a network of membranes within eukaryotic cells that includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, and vesicles, involved in protein and lipid synthesis and transport.

What is NASA's working definition of life?

A self-sustaining chemical system capable of evolution.

What are the three great unifying theories of modern biology?

Cell theory, Chromosomal theory of inheritance, Evolution.

What are the four critical functions of plasma membranes?

1. Protects the cell, 2. Regulates transport, 3. Facilitates communication, 4. Maintains homeostasis.

How do ions and polar molecules move across a lipid bilayer?

They require protein tunnels.

What is the significance of endosymbiosis in eukaryotic evolution?

It led to the formation of mitochondria and chloroplasts in eukaryotic cells.

What is the role of RuBisCo in bioenergetics?

It is the enzyme responsible for fixing carbon from CO2 into biomolecules.

What is the function of ATP synthase?

It captures energy into ATP molecules.

What is a ligand in cell signaling pathways?

A signal molecule that binds to a receptor protein.

What happens to a receptor protein when it binds to a ligand?

It undergoes a shape change that initiates a response in the target cell.

What is the cell cycle?

The series of phases that a cell goes through leading to its division and replication.

What are the phases of Interphase?

G1 (gap 1), S (synthesis), G2 (gap 2).

What occurs during the S phase of the cell cycle?

DNA replication.

What is the significance of G0 phase?

Differentiated cells exit the cell cycle and perform specific functions.

What is the process of DNA replication?

Existing strands of DNA act as templates for new strands, with nucleotides added at the 3' end.

What is the difference between mitosis and meiosis?

Mitosis results in two identical daughter cells, while meiosis results in four genetically diverse gametes.

What does crossing over during meiosis involve?

Exchange of genetic material between non-sister chromatids.

What is the expected phenotype ratio in a monohybrid cross?

3:1 ratio of dominant to recessive phenotypes.

How do you determine if genes are linked in a dihybrid cross?

By observing the ratios of offspring phenotypes and comparing them to expected ratios.

What does the notation 'b+' represent in Drosophila genetics?

The wild type allele for red eyes.

What is the expected outcome when a notched wing female is crossed with a rounded wing male?

All F1 offspring will have notched wings.

What is a molecular switch in cell signaling?

A change in protein shape that alters its function, often triggered by phosphorylation.

What is the role of mutations in gene expression?

Mutations can alter the function of genes, potentially affecting protein synthesis.

What is the purpose of transcription in protein synthesis?

To create an RNA copy of a gene from DNA.

What is the role of translation in protein synthesis?

To synthesize proteins based on the sequence of mRNA.

How do you calculate genetic map distance?

By measuring the frequency of recombination between linked genes.

What are the two types of cell division?

Mitosis and Meiosis.

What is the significance of the 3:1 ratio in F2 offspring?

It indicates that the trait is controlled by a single gene with dominant and recessive alleles.

What type of molecule will most easily cross a plasma membrane by simple diffusion?

A nonpolar small molecule.

In which of the following compartments of eukaryotic cells would you not expect to find nucleic acids?

Golgi Apparatus.

Which of the following are present in eukaryotic cells but not in prokaryotic cells?

Internal membrane-bound compartments.

What is the order of structures a protein passes through for modification and export?

Rough ER; vesicle; Golgi apparatus; vesicle.

What are phospholipids?

Amphipathic molecules with polar heads and non-polar tails that allow small non-polar molecules to diffuse through the cell membrane.

What level of enzyme structure is destroyed by the pH of the cytoplasm?

Tertiary structure.

In a transmembrane protein, where could serine and asparagine be located?

In a hydrophilic cytoplasmic region.

Which biomolecule sequence corresponds to a lipid, an amino acid, a carbohydrate, and a nucleotide?

4, 1, 3, 2.

Where do the light reactions of photosynthesis take place?

In the thylakoid membrane.

During the electron transport chain of cellular respiration, where is H+ pumped in plant cells?

Into the mitochondrial intermembrane space.

What molecule accepts electrons at the end of the respiratory electron transport chain?

Oxygen.

What photosynthetic process most directly generates oxygen (O2)?

Oxidation of water by Photosystem II (P680) chlorophyll in non-cyclic electron transport.

How can you permanently block the function of an enzyme?

By adding a molecule that can covalently bind to the active site.

What does it mean if an enzyme is inhibited by a kinase and activated by a phosphatase?

The kinase adds a phosphate group that inhibits the enzyme, while the phosphatase removes it, releasing the inhibition.

What is the role of a ligand in the epinephrine signaling pathway?

It binds to a receptor to initiate a signaling cascade.

What is a second messenger in cellular signaling?

A molecule that relays signals received at receptors on the cell surface to target molecules inside the cell.

What is the significance of a non-conservative missense mutation in an enzyme?

It can alter the enzyme's active site and affect its function.

What phase of cell division is indicated by a diploid organism with 2n=6 chromosomes?

Metaphase of mitosis.

What is the role of a kinase in enzyme activity?

A kinase generates phosphate that binds to the active site of the enzyme, inhibiting its catalytic activity.

What is the role of a phosphatase in enzyme activity?

A phosphatase decomposes phosphate, thereby removing it and its inhibitory effect on the enzyme.

What happens when a kinase adds a phosphate group to an allosteric site?

It inhibits the enzyme's catalytic activity, while the phosphatase removes the phosphate group to release this inhibition.

What is the effect of a kinase binding to an allosteric site?

It causes a conformational shift that can either increase or decrease the catalytic rate of the enzyme.

What is a ligand in the context of signaling pathways?

A ligand is a molecule that binds to a receptor, initiating a signaling cascade within a cell.

What is a second messenger in cell signaling?

A second messenger is a molecule that transmits signals from a receptor to target molecules inside the cell, amplifying the signal.

What is a non-conservative missense mutation?

A non-conservative missense mutation is a change in a single amino acid in a protein that alters its function, potentially affecting processes like glycogen catabolism.

What is the outcome of a cell in metaphase?

In metaphase, chromosomes are aligned at the cell's equatorial plane, preparing for separation during cell division.

What causes genetic variation in daughter cells from meiosis?

Genetic variation arises from crossover between non-sister chromatids and independent assortment of homologous chromosomes.

What does it mean if lactose intolerance is an autosomal recessive trait?

It means that an individual must inherit two copies of the recessive allele to express lactose intolerance.

What can be inferred if a woman who can digest lactose has lactose intolerant children?

The mother must be a heterozygote, carrying one dominant and one recessive allele for lactose digestion.

What does the inheritance pattern of coat color in cats indicate?

The presence of both black and white kittens suggests that the black male cat is likely heterozygous for coat color.

What determines the coat color in Labrador retrievers?

The coat color is determined by two loci: one for pigment deposition (e) and one for color (B/b).

What is alternative splicing?

Alternative splicing is a process that allows a single gene to produce multiple protein variants by including or excluding certain sequences.

What is the function of transcription factors in gene expression?

Transcription factors are regulatory proteins that must be assembled on the chromosome for RNA polymerase II to initiate transcription.

What is the significance of the sequence of nitrogenous bases in DNA?

The sequence encodes information for amino acids in proteins, transcription regulation, and serves as a template for DNA replication.

What are the promoter and transcription terminator signals?

The promoter initiates transcription, while the transcription terminator signals the end of transcription.

How does RNA polymerase differ from DNA polymerase?

RNA polymerase does not require a primer to initiate synthesis and synthesizes RNA in the 5' to 3' direction, while DNA polymerase requires a primer and also synthesizes DNA in the 5' to 3' direction.

What is RNA polymerase?

An enzyme that synthesizes RNA from a DNA template without requiring a primer.

What is DNA polymerase?

An enzyme that synthesizes DNA from a DNA template and requires a primer to initiate synthesis.

What is a missense mutation?

A mutation that results in the substitution of one amino acid for another in a protein.

What is chromatin arrangement?

The structural organization of DNA and histones that regulates gene expression by making DNA more or less accessible.

What is transcriptional control?

Regulation of gene expression at the transcription level, often involving transcription factors and promoters.

What is post-transcriptional control?

Regulation of gene expression after transcription, including processes like splicing and the addition of 5' caps and poly-A tails.

What is post-translational control?

Regulation of gene expression after translation, which can involve modifications such as phosphorylation and glycosylation.

What is the role of the 5' cap?

A modified guanine nucleotide added to the 5' end of mRNA that protects it from degradation and assists in ribosome binding during translation.

What is the function of a poly-A tail?

A sequence of adenine nucleotides added to the 3' end of mRNA that enhances stability and regulates the export of mRNA from the nucleus.

What is splicing?

The process of removing introns from pre-mRNA and joining exons together to form mature mRNA.