Biology 138 Second Semester Review Flashcards

A comprehensive set of vocabulary flashcards covering DNA structure, protein synthesis, biotechnology, meiosis, genetics, evolution, and body systems based on the semester review transcript.

DNA Shape

A double helix structure.

Nucleotide Components

Consists of deoxyribose sugar, a nitrogen base, and a phosphate group.

Transcription

The process by which DNA is copied onto RNA; involves RNA polymerase and mRNA, occurring in the nucleus.

Translation

The process by which DNA is uncoded from the mRNA and turned into proteins; involves mRNA, tRNA, rRNA, ribosomes, and amino acids in the cytoplasm.

DNA Replication

The process by which the cell makes an exact copy of DNA before it divides using enzymes like Helicase and DNA polymerase.

Helicase

The enzyme responsible for opening the DNA strand during replication.

DNA Polymerase

The enzyme that copies or fills in the DNA strand during replication.

mRNA (messenger RNA)

Molecules that copy DNA code and transport it to the ribosome.

tRNA (transfer RNA)

Molecules that decode the code brought by mRNA.

rRNA (ribosomal RNA)

Molecules that align tRNA and mRNA and سپس create actual proteins.

Mutation

A heritable change in the DNA of an organism caused by various factors.

Missense Mutation

A point mutation that changes one amino acid.

Nonsense Mutation

A point mutation that alters an amino acid codon into a stop codon.

Silent Mutation

A mutation where the base is changed but it still codes for the same protein.

Frameshift Mutation

A mutation caused by insertions or deletions that shift the reading frame.

Genetic Engineering

The direct manipulation of an organism's DNA.

Recombinant DNA

DNA that is taken from one organism and transferred to another, which then uses the DNA as their own.

Restriction Enzymes

Enzymes programmed to cut DNA at specific recognition site sequences, which are usually palindromes.

Transgenic Organism

An organism that contains recombinant DNA from another species.

Plasmid

A bacterial vector that carries genetic information from one organism to another.

Selective Breeding

Breeding organisms to obtain offspring with specific desired traits.

Blunt Ends

DNA fragments cut into two easy halves by restriction enzymes.

Sticky Ends

DNA fragments cut in a way that leaves overhangs, making them useful for recombinant DNA technology.

Gel Electrophoresis

A technique used to separate DNA pieces by size; DNA moves because it has a negative charge.

Diploid ($2n$)

The number of chromosomes in a body cell (e.g., $46$ in humans).

Haploid ($n$)

The number of chromosomes in a gamete (e.g., $23$ in humans).

Crossing Over

The exchange of DNA segments between non-sister chromatids during Prophase I of meiosis.

Reduction Division

A term for Meiosis I because it reduces the number of chromosomes by half.

Spermatogenesis

The final stage of meiosis in males resulting in $4$ functional sperm cells.

Oogenesis

The final stage of meiosis in females resulting in $1$ egg and $2$ to $3$ nonfunctional polar bodies.

Karyotype

A photomicrograph of chromosomes dividing in a cell, used to determine sex and genetic disorders.

Autosomal Chromosomes

Normal chromosomes found throughout the body, excluding sex chromosomes.

Sex Chromosomes

Chromosomes that determine an individual's gender, identified on a karyotype by the presence of a $Y$ chromosome for males.

Zygote

The first stage of life formed when an egg and sperm fuse.

Genetics

The study of traits and inheritance.

Genotype

The specific alleles an organism possesses.

Phenotype

The visible physical expression of a trait.

Incomplete Dominance

A genetic situation where neither allele is dominant, resulting in a blend (e.g., black and white mating to produce gray).

Codominance

A genetic situation where neither allele is dominant, so both traits show up simultaneously.

Heterozygous

An organism having one dominant allele and one recessive allele.

Homozygous

An organism having two identical alleles for a trait.

Homologous Structures

Structures that look the same across different species but differ in function.

Analogous Structures

Structures that look different but serve the same function.

Vestigial Structures

Structures used by an organism's ancestor that are no longer functional in the modern species.

Natural Selection

The process where the environment selects for individuals with the best traits for survival.

Artificial Selection

The process where humans choose specific traits when breeding organisms.

Thorium-230 Half-life

Approximately $75,000\,years$.

Potassium-40 Half-life

Approximately $1300\,million\,years$.

Speciation

The creation of two different species from one original population.

Adaptation

An inherited characteristic that gives a population a survival advantage.

Convergent Evolution

When unrelated organisms look similar due to environmental pressures.

Divergent Evolution

Also known as adaptive radiation; when organisms become less alike after separating from a common ancestor.

Genetic Drift

A change in allele frequency due to random chance events like hunting, natural disasters, or disease.

Age of the Earth

Approximately $4.54\,billion\,years$.

Peristalsis

Wavelike muscle contractions that propel food and waste through the digestive tract.

Villi

Structures in the small intestine that maximize absorption of proteins, carbohydrates, fats, vitamins, and minerals.

Amylase

A digestive enzyme that functions in the mouth to break down carbohydrates.

Pepsin

A digestive enzyme that functions in the stomach to break down proteins.

Arteries

Thick, muscular blood vessels that transport oxygenated blood throughout the body (except pulmonary move deoxygenated).

Veins

Thin-walled blood vessels with valves that carry blood back to the heart.

Capillaries

The smallest and most abundant blood vessels where diffusion takes place.

Erythrocytes

Red blood cells containing hemoglobin to transport $O_2$.

Leukocytes

White blood cells that are phagocytic and ingest harmful bacteria.

Platelets

Cell fragments that clot blood after an injury.