Biology Quiz: DNA Replication and Cell Division

Reproduction Mechanisms

• Reproduction ensures species continuity.
• Mechanisms vary by organism.

Asexual Reproduction

• Involves one parent.
• Offspring are genetically identical to the parent.
• Faster and requires less energy.
• Lower risk to the parent.
• Limited genetic variation: less adaptability to changing environments.
• Methods include binary fission, budding, and spores.

Sexual Reproduction

• Involves two parents.
• Offspring are genetically different from parents.
• Requires finding a partner and more energy.
• Higher risk than asexual reproduction.
• Increased genetic variation: greater adaptability to changing environments.
• Methods include external and internal fertilization, seeds, and spores.

Unicellular Organisms

• Bacteria reproduce asexually through binary fission.
• Protists often reproduce asexually through binary fission or budding.
• Genetic material transfers via direct contact between cells.

Multicellular Organisms

• Fungi reproduce asexually through spores.

• Occurs in stressful environments, hence less genetic variability.

• Involves two haploid cells from different mycelia that fuse.

• Fungi then produce haploid spores.

• Plants reproduce asexually using bulbs, corms, tubers, runners, and cuttings.

• Plants reproduce sexually via spores or seeds in flowering plants and conifers.

• external fertilization requires water, spores or seeds produced

• Internal fertilization does not require water, and involves reproduction within the body of the parent.

Animal Reproduction

• External fertilization: common in aquatic animals like fish and amphibians.
• Internal fertilization: common in terrestrial animals like mammals, birds, and reptiles.
• Large numbers of gametes and strategies may increase survival.
• Environmental triggers may impact timing and location of reproduction.

Plant Reproduction

• Bulbs: storage organs at the base of plants.
• Corms: similar to bulbs but solid without layers.
• Tubers: underground stems that store food.
• Rhizomes: underground stems that spread sideways.
• Runners: stems spreading sideways and forming new plants.
• Cuttings: pieces of a plant grown into new plants.
• Layering: stems develop roots when touching the soil.

Plant Sexual Reproduction

• Involves flowers, pollen, and ovules.
• Pollination occurs via wind, water, or animals.
• Fertilization is followed by seed dispersal for offspring survival and spread into new environments.

DNA Replication

• DNA polymerase replicates DNA using a template strand, producing new strands identical to the original.

Cell Cycle and Cell Division

• Mitosis: produces two identical diploid daughter cells, crucial for growth and repair.
• Stages: Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis.
• Meiosis: produces four haploid daughter cells, crucial for sexual reproduction.
• Further divided into Meiosis I and Meiosis II. stages.

Genetic Variation

• Crossing over: during meiosis, homologous chromosomes exchange segments, increasing diversity.
• Fertilization: random combination of alleles from each parent.
• Mutations: changes in DNA sequence, contributing to new alleles and genetic variation.

Genetic Variation in Populations

• Autosomal traits: located on non-sex chromosomes.
• Sex-linked traits: located on sex chromosomes.
• Co-dominance: both alleles are equally expressed in the phenotype (e.g., blood types).
• Incomplete dominance: neither allele is completely dominant, resulting in a blended phenotype (e.g., flower color).
• Multiple alleles: more than two alleles for a single gene exist.

DNA Replication

• DNA polymerase replicates DNA using a template strand, producing new strands identical to the original.

Polypeptide Synthesis

• Transcription: DNA code is copied into mRNA in the nucleus.
• Translation: mRNA leaves the nucleus to a ribosome in the cytoplasm, where its code is translated into a sequence of amino acids by tRNA.
• mRNA carries genetic information from DNA to ribosomes to assemble amino acids into proteins.
• tRNA carries amino acids to the ribosome and matches them to the mRNA codons.

Protein Structure

• Proteins have a primary structure consisting of amino acids in a specific order.
• Interactions lead to secondary structures like alpha-helices and beta-sheets.
• Further folding creates tertiary structures.
• Some proteins have quaternary structures when multiple polypeptide chains come together.

Hormonal Control of Pregnancy and Birth

• Hormones act as chemical messengers, regulating bodily processes.
• Hormones regulate the reproductive cycle and pregnancy progression.
• Placenta plays a crucial role in supplying nutrients to the developing fetus and maintaining the balance of hormones.
• Hormones like estrogen and progesterone regulate reproductive processes.
• The changing levels of hormones are crucial to regulate pregnancy and birth.

Inheritance Patterns in a Population

• Gene flow: The movement of alleles between populations.
• Genetic drift: random fluctuations in allele frequencies within a population.
• Mutations: changes in DNA sequence, introducing new alleles into a population

Infectious Diseases

• Cellular pathogens: Bacteria, Fungi, Protozoa.
• Non-cellular pathogens: Viruses, Prions.
• Transmission: Direct, Indirect, Vector-borne.
• Epidemiology: studies of disease patterns in populations.

Immunity

• Innate immunity: Provides immediate, non-specific defense.
• Physical barriers, chemical barriers, inflammation, complement system.
• Adaptive immunity: Provides specific defense, developed after exposure to a pathogen.
• Cellular response (T cells), Antibody response (B cells), Memory cells.