Eukaryotes and Prokaryotes, Cell Cycle, Genetics, and Molecular Biology

A comprehensive set of flashcards covering key concepts in biology, including cellular structures, processes, genetics, and molecular biology, based on lecture notes.

What is the key difference between prokaryotes and eukaryotes?

Eukaryotes have a nucleus and membrane bound organelles, prokaryotes do not.

Where is DNA located in a prokaryotic cell?

In the nucleoid region in the cytoplasm.

Where is DNA located in a eukaryotic cell?

Inside the nucleus.

What structures do all cells have in common?

DNA, RNA, ribosomes, cytoplasm, and a plasma membrane.

What is the difference between cytosol and cytoplasm?

Cytosol is the liquid; cytoplasm is the liquid plus everything in it (organelles and structures).

Why do eukaryotic cells benefit from compartmentalization?

Different organelles separate tasks, so processes run more efficiently and safely.

You see DNA floating with no nucleus. What type of cell is it?

Prokaryotic.

You see a nucleus plus many internal membrane compartments. What type of cell is it?

Eukaryotic.

What does the nucleus do?

Stores DNA and is where transcription happens.

What do mitochondria do?

Make ATP through cellular respiration.

What does rough ER do?

Synthesizes proteins for secretion or membranes (ribosomes attached).

What does smooth ER do?

Synthesizes lipids and helps with detoxification.

What does the Golgi apparatus do?

Modifies, sorts, and ships proteins.

What do lysosomes do?

Break down macromolecules and worn out cell parts.

A cell makes a secreted protein. What path does it usually follow?

Rough ER to Golgi to vesicle to outside the cell.

What is the cytoskeleton?

A network of protein fibers that gives structure and helps movement inside the cell.

What do microtubules do in cell division?

Form the spindle that moves chromosomes.

Centrosomes are damaged. What is most directly affected?

Spindle formation and chromosome separation.

During mitosis you see long fibers pulling chromosomes apart. What are those fibers?

Microtubules (spindle fibers).

What is the purpose of the cell cycle?

Grow, copy DNA, and divide.

What happens in interphase?

Growth and DNA replication (includes G1, S, G2).

What happens in S phase?

DNA is replicated.

What is M phase?

Mitosis plus cytokinesis.

A cell is preparing to divide but has not replicated DNA yet. What phase must it enter next to copy DNA?

S phase.

What is the goal of mitosis?

Produce two genetically identical daughter cells.

What separates during mitosis?

Sister chromatids.

What happens in prophase?

Chromosomes condense and spindle begins forming.

What happens in metaphase?

Chromosomes line up in the middle.

What happens in anaphase?

Sister chromatids separate to opposite poles.

What happens in telophase?

Nuclei reform and chromosomes decondense.

What is cytokinesis?

Dividing the cytoplasm into two cells.

You observe sister chromatids pulling apart. What phase is this?

Anaphase.

Skin wound healing is happening. Which process is occurring?

Mitosis.

What is the goal of meiosis?

Produce haploid gametes for sexual reproduction.

What makes meiosis different from mitosis?

Meiosis makes 4 nonidentical haploid cells and includes homolog separation and recombination.

What separates in meiosis I?

Homologous chromosomes.

What separates in meiosis II?

Sister chromatids.

Why does meiosis create genetic variation?

Crossing over and independent assortment.

Sperm and egg production uses what division?

Meiosis.

You observe homologous pairs separating. What stage is this most consistent with?

Anaphase I.

What is nondisjunction?

Failure of chromosomes to separate properly during anaphase.

What is first division nondisjunction?

Homologs fail to separate in meiosis I.

What is second division nondisjunction?

Sister chromatids fail to separate in meiosis II.

What is aneuploidy?

Abnormal number of chromosomes.

Meiosis I looks normal, but meiosis II fails. What is this called?

Second division nondisjunction.

A gamete has an extra chromosome. What general error caused it?

Nondisjunction.

What is a gene?

A DNA sequence that affects a trait.

What is an allele?

A version of a gene.

What is genotype?

The allele combination.

What is phenotype?

The observable trait.

What does homozygous mean?

Two of the same allele.

What does heterozygous mean?

Two different alleles.

What does true breeding mean?

Homozygous, offspring show the same trait when self crossed.

What does dominant mean?

One copy shows the trait.

What does recessive mean?

Trait shows only with two copies.

If someone shows a recessive phenotype, what is their genotype?

Homozygous recessive.

If someone shows a dominant phenotype, what genotypes are possible?

Homozygous dominant or heterozygous.

What is the law of segregation?

Allele pairs separate so each gamete gets one allele.

What is the law of independent assortment?

Alleles of different genes assort independently if the genes are not linked.

What does a Punnett square help you predict?

Genotype and phenotype probabilities of offspring.

A heterozygous dominant is crossed with a homozygous recessive. What phenotype ratio is expected?

1 dominant : 1 recessive.

You cross a dominant phenotype with a homozygous recessive and half the offspring are recessive. What is the unknown genotype?

Heterozygous.

What does probability multiply rule mean for two independent events?

Multiply probabilities (example: chance of aa AND bb).

What does a pedigree show?

Inheritance of a trait across generations.

What pattern suggests autosomal recessive?

Trait can skip generations, affected children can come from unaffected parents.

What pattern suggests autosomal dominant?

Trait usually appears every generation, an affected person usually has an affected parent.

In a pedigree, two unaffected parents have an affected child. What inheritance is most likely?

Autosomal recessive.

Why do X linked traits show different patterns than Mendel’s pea traits?

Males have one X, so recessive alleles show more often in males.

Why are males more commonly affected by X linked recessive traits?

They only need one recessive allele on their single X.

Can an X linked trait be passed father to son directly?

No, fathers pass Y to sons, not X.

If a mother is a carrier for an X linked recessive trait, who is more likely to be affected, sons or daughters?

Sons.

A trait appears mostly in males and never passes father to son. What is likely?

X linked recessive.

What does it mean if genes are linked?

They are on the same chromosome and tend to be inherited together.

What does crossing over do?

Exchanges segments between homologous chromosomes, creating recombinants.

How does distance between two genes affect recombination?

Farther apart means more recombination, closer means less.

If two genes are very close together, what gametes are most common?

Parental (nonrecombinant) gametes.

If two genes are far apart, what happens to recombinant frequency?

It increases, approaching 50 percent.

You see fewer recombinant offspring than expected by independent assortment. What is the best explanation?

The genes are linked.

What are the four DNA bases?

A, T, G, C.

Which bases are purines?

A and G.

Which bases are pyrimidines?

C and T.

What are base pairing rules?

A with T, G with C.

Which base pair has more hydrogen bonds?

G C has 3, A T has 2.

Why is GC rich DNA harder to separate?

More hydrogen bonding and stronger stacking.

What is meant by antiparallel strands?

One runs 5 prime to 3 prime, the other runs 3 prime to 5 prime.

Why does antiparallel matter for transcription and replication?

Polymerases can only build 5 prime to 3 prime, so direction determines how templates are used.

What happens during DNA denaturation?

Strands separate.

What bonds are disrupted first during denaturation?

Hydrogen bonds and base stacking, not the covalent backbone.

What can cause denaturation?

Heat, extreme pH, and chemicals that disrupt interactions.

What is the central dogma?

DNA to RNA to protein.

What is an example of an exception to the central dogma?

Reverse transcription (RNA to DNA) in retroviruses.

What are introns?

Noncoding regions removed from pre mRNA.

What are exons?

Coding regions kept and joined.

What is splicing?

Removing introns and joining exons.

What is the purpose of the 5 prime cap?

Protects mRNA and helps ribosome binding.

What is the purpose of the poly A tail?

Increases stability and helps export and translation.

What is alternative splicing?

Different exon combinations make different proteins from one gene.

What enzyme performs transcription?

RNA polymerase.

What direction is RNA synthesized?

5 prime to 3 prime.

What direction is the template strand read?

3 prime to 5 prime.