Biology Notes: Photosynthesis, Energy, DNA/RNA, Cell Division & Genetics

Vocabulary flashcards covering key terms and definitions from the lecture notes on photosynthesis, energy flow, DNA/RNA, cellular respiration, chromosomes & cell division, and genetics.

Autotrophs

Organisms that make their own food (e.g., plants, algae, some bacteria).

Heterotrophs

Organisms that consume other organisms for energy (e.g., animals, fungi).

Chloroplast

Organelle where photosynthesis occurs; contains stroma and thylakoids.

Stroma

Fluid inside the chloroplast surrounding the thylakoids.

Thylakoids

Flattened sacs inside chloroplasts; stacked into grana.

Grana

Stacks of thylakoids within the chloroplast.

Light reaction

Photosynthetic stage where chlorophyll absorbs light, exciting electrons to produce ATP and NADPH.

Chlorophyll

Pigment that absorbs light during photosynthesis.

Oxygen source

Oxygen released when water is split during the light reactions.

Water

Molecule split in photosynthesis to provide electrons and oxygen.

Proton pumps

Move H+ into the thylakoid space to generate a proton gradient.

ATP synthase

Enzyme that uses the proton gradient to synthesize ATP.

Calvin cycle

Dark reactions that build sugars using ATP and NADPH from the light reactions.

NADPH

Electron carrier produced in light reactions; used in the Calvin cycle.

ATP

Adenosine triphosphate; main energy currency; energy released when converted to ADP.

Glucose

Sugar produced by photosynthesis and used as fuel in respiration.

Acetyl-CoA

Two-carbon molecule that enters the Krebs Cycle by combining with oxaloacetate.

Krebs Cycle

Mitochondrial matrix cycle that processes acetyl-CoA to CO2 and energy carriers (NADH, FADH2).

Citric acid

Six-carbon molecule formed when acetyl-CoA combines with oxaloacetate.

Oxaloacetate

Four-carbon molecule that combines with acetyl-CoA to form citric acid.

NADH

Electron carrier that delivers electrons to the Electron Transport Chain.

FADH2

Electron carrier that delivers electrons to the Electron Transport Chain.

ETC

Electron Transport Chain; generates ATP via oxidative phosphorylation in the inner mitochondrial membrane.

Glycolysis

Glucose breakdown in the cytoplasm to pyruvate, yielding a small amount of ATP and NADH.

Pyruvate

End product of glycolysis; enters mitochondria for the Krebs cycle or fermentation.

Cytoplasm

Location where glycolysis occurs.

Fermentation

Anaerobic process that regenerates NAD+ when oxygen is unavailable.

Lactic acid

Fermentation product in animals (muscle) causing fatigue.

Ethanol

Fermentation product in yeast plus CO2.

Carbon dioxide (CO2)

Gas released from the Krebs Cycle and fermentation.

Water (H2O)

Water produced at the end of the Electron Transport Chain.

Chromatin

DNA wrapped around histones; form of DNA packaging.

Histones

Proteins around which DNA winds to form chromatin.

Centromere

Region that holds sister chromatids together.

Diploid (2n)

Full set of chromosomes (46 in humans).

Haploid (n)

Half set of chromosomes (23 in humans).

Binary fission

Asexual cell division in bacteria.

Interphase

Stage when the cell spends most of its life growing and DNA is replicated.

PMAT

Prophase, Metaphase, Anaphase, Telophase — stages of mitosis.

Mitosis

Cell division producing two identical diploid daughter cells.

Meiosis

Cell division producing four unique haploid gametes; PMAT occurs twice.

Crossing over

Exchange of DNA between homologous chromosomes in Prophase I of meiosis.

Phenotype

Physical traits expressed by an organism.

Genotype

Genetic makeup; alleles present for a gene.

Alleles

Different versions of a gene.

Dominant

Trait expressed when at least one copy is present.

Recessive

Trait expressed only when two copies are recessive (homozygous).

Homozygous

Two identical alleles (AA or aa).

Heterozygous

Two different alleles (Aa).

Monohybrid cross

Cross examining one trait.

Dihybrid cross

Cross examining two traits.

Pedigree

Family tree used to track inheritance patterns.

Circles indicate female

In pedigrees, circles represent females.

Squares indicate male

In pedigrees, squares represent males.

Shaded trait expressed

Shaded symbols indicate individuals who express the trait.

DNA

Double-stranded nucleic acid; stores genetic information.

RNA

Single-stranded nucleic acid; involved in protein synthesis.

mRNA

Messenger RNA; carries genetic code from DNA to ribosome.

rRNA

Ribosomal RNA; component of ribosomes.

tRNA

Transfer RNA; brings amino acids to the ribosome.

Transcription

Process of copying DNA into mRNA in the nucleus.

Translation

Process of protein synthesis where ribosomes read mRNA to assemble amino acids.

Covalent bond

Electrons are shared; a strong bond in biology.

Hydrogen bond

Weak attraction between a hydrogen and an electronegative atom; important in DNA base pairing.

Ionic bond

Bond formed by electrical attraction between charged ions.