BIO 1C Exam 1 HELP

What are the general steps of the scientific method?

Observation, Question, Hypothesis, Prediction, Experiment, Analysis, Conclusion.

What makes a hypothesis testable and falsifiable?

It can be tested experimentally and could potentially be proven wrong.

What is the different between a hypothesis and a theory?

A hypothesis is a testable explanation and a theory is a well-supported explanation backed by evidence.

Why do scientists usually avoid saying a hypothesis is “proven”?

Scientific conclusions can always be revised with new evidence.

What are the three main statements of cell theory?

All living organisms are made of cells. The cell is the basic unit of life. All cells arise from preexisting cells.

What components must a structure have to be considered a cell?

Plasma membrane, cytoplasm, and genetic material (DNA)

What are the characteristics of life?

Cellular organization, metabolism, homeostasis, growth, reproduction, response to stimuli, adaption, and heredity.

What are the three domains of life?

Bacteria, Archaea, and Eukarya.

What are the main differences between prokaryotic and eukaryotic cells?

Prokaryotes lack a nucleus and membrane-bound organelles. Eukaryotes have both.

What is the central dogma of molecular biology?

DNA, RNA, Protein

What is the biological definition of evolution?

A change in the genetic composition of a population across generations.

What four mechanisms can cause evolution?

Mutation, natural selection, genetic drift, and gene flow.

What is natural selection?

Individuals with advantageous traits survive and reproduce more successfully than others.

What is fitness in evolutionary biology?

An organism’s reproductive success relative to others.

How could you determine if differences between two fish populations are due to evolution?

Compare genetic sequences across generation and determine the frequencies of heritable traits.

What are the three main subatomic particles and their charges?

Protons +, Neutrons 0, Electrons -

What determines the atomic number of an atom?

The number of protons.

What determines the mass number of an atom?

Protons and neutrons.

What is an isotope?

Atoms of the same element with different numbers of neutrons

What is the difference between an ionic bond and a covalent bond?

Ionic bonds involve electron transfer; covalent bonds involve electron sharing.

What is molarity?

Moles/liters

Why are hydrogen bonds important in biological systems?

They stabilize protein structures, DNA double helix, and properties of water.

How do buffers maintain stable pH?

They accept or donate hydrogen ions to resist changes in pH.

Why can some insects walk on water?

Because of water’s strong surface tension due to hydrogen bonding.

What property of carbon makes it essential for life?

It can form four stable covalent bonds, allowing complex molecules.

What are the four major biological macromolecules?

Carbohydrates, lipids, proteins, nucleic acids.

Which macromolecules are true polymers?

Proteins, nucleic acids, and carbohydrates.

What type of bond connects amino acids?

Peptide bond.

What type of bond connects monosaccharides?

Glycosidic bond.

What type of bond connects nucleotides?

Phosphodiester bond.

Why can’t humans digest cellulose?

Humans lack enzymes tat break beta-1,4 glycosidic bonds.

What are the main structural differences between DNA and RNA?

DNA has deoxyribose and thymine while RNA has ribose and uracil.

What are the four levels of protein structure?

Primary, secondary, tertiary, and quaternary.

What stabilizes secondary protein structure?

Hydrogen bonds.

What determines a protein’s final shape?

Amino acid sequence.

What is transcription?

The process of synthesizing RNA from DNA template.

What enzyme performs transcription?

RNA polymerase.

What are the three stages of transcription?

Initiation, Elongation, Termination.

What happens during mRNA processing in Prokaryotes?

5’ cap added, poly-A tail added, introns removed, exons spliced together.

What is alternative splicing?

Different combinations of exons can produce different proteins from the same gene.

What is translation?

The process of synthesizing a protein from mRNA.

What is the start codon?

AUG (methionine)

What are the stop codons?

UAA, UAG, UGA

What does degeneracy of the genetic code mean?

Multiple codons can encode the same amino acid.

How many nucleotides are needed for 12 codons?

36 nucleotides

When would you use a compound light microscope?

To observe living cells and cell movement.

When would you use a scanning electron microscope (SEM)?

To observe 3_D surface structure.

When would you use a transmission electron microscope (TEM)?

To view internal cell structures in high detail.

What structures are part of the endomembrane system?

Nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, plasma membrane.

What structures are not part of the endomembrane system?

Mitochondria, chloroplasts, ribosomes, cytoskeleton

Why are plasma membranes arranged as a phospholipid bilayer?

Phospholipids are amphipathic with hydrophilic heads and hydrophobic tails.

What does “form follow function” mean in cell biology/

The structure of a biological component is adapted to its function.

What structures separate plant, animal, and bacterial cells from their environment?

Cell Wall (except for animal cells) and Plasma membrane

Why do phospholipids spontaneously form membranes in water?

Hydrophobic tails avoid water while hydrophilic heads interact with it.

Why do ions struggle to cross membranes?

The membrane interior is hydrophobic and repels charged particles.

What DNA strand is used as the template during transcription?

The DNA template strand which RNA polymerase reads to build RNA.

Why is RNA almost identical to the DNA non-template strand?

RNA is complementary to the template strand, matching the non-template strand.

Why must mRNA be processed before leaving the nucleus in eukaryotes?

Processing protects the mRNA, removes introns, and prepares it for translation.

What is the purpose of the ribosome during translation?

The ribosome reads the mRNA codons and links amino acids together to form a protein.

Why must tRNA molecules match the mRNA codons correctly?

Each codon determines which amino acid is added to the growing protein.

What determines the order of amino acids in a protein?

The sequence of codons in mRNA.

What would happen if the start codon is mutated or missing?

The ribosome may not being translation, so no protein would be produced.

Why does translation stop when a stop codon is reached?

There is no tRNA that matches stop codons, so a release factor ends protein synthesis