BIO Lab Midterm Review – Vocabulary

Vocabulary flashcards covering genetics, cell division, cellular respiration, photosynthesis, and membrane transport for the BIO Lab midterm.

Diploid

A cell containing two complete sets of chromosomes (2n), one set inherited from each parent.

Homologous pair

Two chromosomes of the same size and structure that carry the same genes but may have different alleles.

Dominant allele

An allele whose trait is expressed in the phenotype whenever it is present.

Recessive allele

An allele whose trait is masked in the phenotype when a dominant allele is also present.

Genotype

The genetic makeup of an organism; the combination of alleles it possesses.

Phenotype

The observable physical or biochemical characteristics of an organism, determined by genotype and environment.

Homozygous dominant

Having two dominant alleles for a given gene (e.g., AA).

Heterozygous

Having one dominant and one recessive allele for a given gene (e.g., Aa).

Homozygous recessive

Having two recessive alleles for a given gene (e.g., aa).

Incomplete dominance

Inheritance pattern in which neither allele masks the other, resulting in an intermediate phenotype.

Punnett square

A diagram used to predict the genotypes and phenotypes of offspring from a genetic cross.

Pedigree

A family tree diagram that shows the inheritance of a trait through generations.

Meiosis

A two-division process that reduces chromosome number by half to form haploid gametes for sexual reproduction.

Homologous chromosomes

Chromosome pairs, one from each parent, that carry the same genes but possibly different alleles.

Karyotype

An ordered visual display of all chromosomes in a cell, showing number and structure (46 chromosomes in humans).

Gamete

A haploid sex cell (sperm or egg) produced by meiosis.

Zygote

The diploid cell formed when two gametes fuse during fertilization.

Crossing over

Exchange of genetic material between homologous chromosomes during prophase I of meiosis, increasing genetic variation.

Independent assortment

Random orientation of homologous chromosome pairs during metaphase I, producing varied gamete combinations.

Nondisjunction

Failure of homologous chromosomes or sister chromatids to separate properly, leading to abnormal gametes.

Haploid

A cell containing one complete set of chromosomes (n).

Telophase I

Stage in meiosis I when chromosomes reach poles and new nuclei form around them.

Cytokinesis

Division of the cytoplasm, producing two (or four) daughter cells after mitosis or meiosis.

Monozygotic twins

Identical twins that develop from one zygote splitting into two embryos; genetically identical.

Dizygotic twins

Fraternal twins that develop from two different zygotes; genetically unique like siblings.

Mitosis

Nuclear division producing two genetically identical diploid daughter cells for growth, repair, or asexual reproduction.

Cell cycle

The repeating sequence of growth, DNA replication, and division in a cell (Interphase + Mitosis/Cytokinesis).

Interphase

Portion of the cell cycle when the cell grows, performs normal functions, and replicates DNA (G1, S, G2).

G1 phase

First gap phase; cell grows and carries out normal metabolism, protein synthesis.

S phase

Synthesis phase; DNA replication occurs, committing the cell to division.

G2 phase

Second gap phase; cell produces proteins necessary for mitosis and prepares to divide.

Prophase

Mitosis stage where chromosomes condense and the spindle apparatus forms.

Metaphase

Mitosis stage where spindle aligns duplicated chromosomes along the cell’s equator.

Anaphase

Mitosis stage where sister chromatids separate and move toward opposite poles.

Telophase

Mitosis stage where chromosomes de-condense, nuclear envelopes re-form, and spindle breaks down.

Cleavage furrow

Indentation that forms in animal cells during cytokinesis to divide the cytoplasm.

Cell plate

Structure that forms in plant cells during cytokinesis, giving rise to a new cell wall.

Cancer

Disease characterized by uncontrolled cell division due to cell-cycle regulation failures.

ATP (Adenosine Triphosphate)

Main energy currency of the cell, powering muscle movement, active transport, and chemical reactions.

Aerobic cellular respiration

Process that uses oxygen to break down glucose, generating CO₂, H₂O, and ~36–38 ATP.

Glycolysis

First stage of respiration; splits glucose into 2 pyruvate in the cytoplasm, netting 2 ATP and 2 NADH.

Transition step

Conversion of pyruvate to acetyl CoA, producing CO₂ and NADH in the mitochondrial matrix.

Krebs cycle

Series of reactions in the mitochondrial matrix that oxidize acetyl CoA, yielding CO₂, NADH, FADH₂, and ATP.

Electron transport chain (ETC)

Inner mitochondrial membrane pathway that uses electrons from NADH/FADH₂ to make most cellular ATP and water.

Fermentation

Anaerobic pathway that regenerates NAD⁺ and yields 2 ATP per glucose when oxygen is absent.

Lactic acid fermentation

Anaerobic process in muscle cells and some bacteria that converts pyruvate to lactic acid.

Alcoholic fermentation

Anaerobic process in yeast and microbes that converts pyruvate to ethanol and CO₂.

Photosynthesis

Process in chloroplasts that converts light, water, and CO₂ into glucose, releasing O₂.

Thylakoid

Membranous sac in chloroplasts where light-capturing pigments and photosystems reside.

Light reactions

First stage of photosynthesis; converts light energy to chemical energy (ATP, NADPH) and releases oxygen.

Carbon reactions (Calvin cycle)

Second stage of photosynthesis; uses ATP and NADPH to fix CO₂ into carbohydrates.

Entropy

Measure of disorder; energy transformations increase the universe’s entropy.

Metabolism

All chemical reactions that occur within living cells.

Oxidation

Reaction that loses electrons and releases energy.

Reduction

Reaction that gains electrons and requires energy input.

Enzyme

Protein catalyst that speeds up chemical reactions by lowering activation energy.

Inhibitor

Molecule that decreases or stops enzyme activity, shutting down unneeded reactions.

Gradient

Difference in concentration, pressure, or charge between two regions.

Simple diffusion

Passive movement of molecules from high to low concentration without energy input.

Osmosis

Passive diffusion of water across a selectively permeable membrane.

Isotonic

Solution with equal solute concentration compared to the cell; no net water movement.

Hypertonic

Solution with higher solute concentration than the cell; water leaves the cell.

Hypotonic

Solution with lower solute concentration than the cell; water enters the cell.

Facilitated diffusion

Passive transport of molecules via membrane proteins down their concentration gradient.

Active transport

Energy-requiring movement of substances against their concentration gradient via transport proteins.

Endocytosis

Active process where the cell membrane engulfs material to bring it inside the cell.

Exocytosis

Active process where vesicles fuse with the plasma membrane to expel materials out of the cell.