Higher Biology

Structure of DNA

Double helix, nucleotide bases: A-T, C-G.

Prokaryotic vs Eukaryotic Cells

Prokaryotic: no nucleus, no organelles. Eukaryotic: has nucleus and membrane-bound organelles.

DNA Location in Prokaryotes

Cytoplasm, circular chromosome, plasmids.

Gene Definition

DNA segment encoding a protein or RNA.

Nitrogenous Bases in DNA

Adenine, Thymine, Cytosine, Guanine.

Base Pairing

A pairs with T; C pairs with G.

Histones

Proteins packaging DNA into nucleosomes.

DNA Nucleotide Components

Phosphate group, deoxyribose sugar, nitrogenous base.

5’ and 3’ Ends of DNA

5’ end: phosphate; 3’ end: sugar.

Plasmids

Small circular DNA in prokaryotes, replicate independently.

Cellular Differentiation

Cells express specific genes to become specialized.

Stem Cell Self-Renewal

Embryonic stem cells can replicate indefinitely.

Research Uses of Stem Cells

Model cells for disease research, drug testing.

Meristems

Unspecialized plant cells that can divide/differentiate.

Stem Cell Ethics

Embryo destruction raises ethical concerns.

Embryonic Stem Cells

Pluripotent, can differentiate into any cell type.

Tissue Stem Cells

Multipotent, replenish specific tissue cells.

Therapeutic Uses of Stem Cells

Repair diseased or damaged tissues/organs.

DNA Replication Process

Occurs before mitosis; ensures identical genetic copies.

Polymerase Chain Reaction (PCR)

Amplifies DNA; priming, denaturation, extension cycles.

Gene Expression Steps

Transcription: DNA to mRNA; Translation: mRNA to protein.

Alternative RNA Splicing

Different proteins from the same mRNA transcript.

Mutations

Changes in DNA; can affect protein sequence.

Natural Selection

Survival increases beneficial traits in populations.

Speciation

New species forms through isolation and mutation.

Gene Expression Involvement

Transcription and translation processes to create proteins from DNA.

Function of rRNA

Structural and functional component of ribosomes; aids in protein synthesis.

Transcription Process

DNA is copied into mRNA by RNA polymerase; occurs in the nucleus.

Role of RNA Polymerase

Enzyme that synthesizes mRNA from the DNA template during transcription.

Translation Process

mRNA is decoded by ribosomes to synthesize proteins; uses tRNA.

Alternative Splicing Process

mRNA processing to produce different proteins from the same gene.

Function of a Meristem

Region of undifferentiated cells in plants that can divide and differentiate.

Multipotent Definition

Ability of tissue stem cells to develop into a limited range of cell types.

Natural Selection Definition

Process where organisms with beneficial traits survive and reproduce.

Natural Selection in Prokaryotes

Beneficial mutations increase survival and reproduction in changing environments.

Species Definition

Group of organisms that can interbreed and produce fertile offspring.

Speciation Process

Formation of new species; occurs when gene flow is interrupted by barriers.

Importance of Isolation Barrier

Prevents interbreeding between populations, leading to divergence.

Types of Speciation

Allopatric, sympatric; caused by geographical, ecological, or behavioral barriers.

Evidence for Evolution Sequence

Fossil records, genetic similarities, embryology, and comparative anatomy.