Biology Cells and DNA Quiz

Biology Checklist

• Topics covered in the biology course are listed, including cells (eukaryotic/prokaryotic, organelles, surface area to volume ratio, osmosis), DNA (structure and function), cell division (mitosis and meiosis), inheritance (dominant/recessive, Punnett squares, pedigrees), evolution (natural selection, adaptations, speciation, fossils).

Cells - Prokaryotes and Eukaryotes

• Prokaryotes are unicellular organisms lacking a membrane-bound nucleus and other membrane-bound organelles.
• Eukaryotic cells have a true nucleus and various membrane-bound organelles.
• Prokaryotes have DNA in a nucleoid region; eukaryotes have DNA in a nucleus.
• Prokaryotic cells are generally smaller (0.1 to 5.0 micrometres) than eukaryotic cells (10 to 100 micrometres or more).
• Examples of prokaryotes: bacteria (e.g., Escherichia coli), archaea (e.g., methanogens).
• Examples of eukaryotes: animals (e.g., humans), plants (e.g., oak trees), fungi (e.g., mushrooms), protists (e.g., amoebas).

Cell Organelles in Plant and Animal Cells

• Cell organelles are specialized structures that perform specific functions crucial for cellular survival.
• Cell organelles commonly found in both plant and animal cells include mitochondria (energy production), chloroplasts (photosynthesis), endoplasmic reticulum (protein and lipid synthesis), Golgi apparatus (protein and lipid processing), lysosomes (waste disposal).
• Plant cells have unique structures such as cell walls and chloroplasts, not found in animal cells.
• Cell size is essential for maintaining efficient cellular functions. As a cell grows, its volume increases faster than its surface area, limiting material transport.

Osmosis: Process and Applicability in Cells

• Osmosis is the movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration, until equilibrium is reached.
• Osmosis plays a crucial role in maintaining cell turgor and overall cellular homeostasis
• Tonicity (hypertonic, hypotonic, isotonic) describes the relative solute concentrations inside and outside a cell affecting the movement of water in and out of the cell.
• Hypertonic solution has a higher solute concentration than a cell, causing water to leave the cell, resulting in shrinkage.
• Hypotonic solution has a lower solute concentration than a cell, causing water to move into the cell, leading to swelling or lysis, which is harmful.
• Isotonic solution has an equal concentration of solutes as a cell, preventing net water movement, maintaining normal cell shape and function.

DNA Structure and Function

• DNA is structured as a double-stranded helix. Each strand consists of nucleotides containing sugar (deoxyribose), phosphate, and nitrogenous bases (adenine, thymine, cytosine, guanine).
• Base-pairing rule: adenine pairs with thymine, cytosine pairs with guanine.
• DNA serves as the hereditary material for development and functioning of living organisms.
• DNA replicates, allowing genetic information to be passed to the next generation.
• DNA is involved in protein synthesis through transcription and translation.

Cell Division (Mitosis)

• Mitosis is the process of cell division that results in two genetically identical daughter cells.
• Mitosis stages include interphase (preparation), prophase (chromosome condensation), metaphase (chromosome alignment), anaphase (chromosome separation), and cytokinesis (cytoplasm division).
• Interphase (part of the overall cell cycle, but not mitosis itself) are the steps before mitosis begins and include G1, S, and G2 phases
• G1 phase: preparation for DNA synthesis
• S phase: DNA replication
• G2 phase: further preparation for cellular division.
• Prophase: Chromatin condenses into visible chromosomes. Nuclear envelope breaks down. Spindle fibres form.
• Metaphase: Chromosomes line up along the metaphase plate. Spindle fibres attach to centromeres.
• Anaphase: Sister chromatids separate and move towards opposite poles. Spindle fibres shorten.
• Cytokinesis: Cytoplasm divides to form two daughter cells.

Cell Division (Meiosis)

• Meiosis is the specialized cell division resulting in four non-identical haploid gamete cells (e.g., sperm and egg).
• Meiosis I separates homologous chromosomes, reducing the chromosome number. Meiosis II separates sister chromatids.
• Meiosis I stages include Interphase (DNA replication), Prophase I (chromosome condensation, homologous pairing, crossing over), Metaphase I (tetrad alignment), Anaphase I (separation of homologous chromosomes), and Cytokinesis I (cytoplasm division).
• Meiosis II stages include Prophase II (chromosome condensation), Metaphase II (individual chromosome alignment), Anaphase II (Separation of sister chromatids), and Cytokinesis II (cytoplasm division).

Inheritance

• Inheritance is the process of passing genetic information from parents to offspring.
• Key concepts: genes, alleles (different versions of a gene).
• Genotype: the genetic makeup of an organism.
• Phenotype: the observable characteristics expressed by an organism.
• Co-dominance, Incomplete Dominance, Dominant/Recessive Traits, Punnett Squares, Pedigree Charts are discussed.
• Co-dominance: both alleles equally contribute to the phenotype.
• Incomplete dominance: the heterozygote phenotype is intermediate between the two homozygotes.
• Dominant traits are expressed even in heterozygous conditions.
• Recessive traits are expressed in homozygous conditions.
• Punnett squares are used to predict the probability of offspring inheriting particular traits.
• Pedigree charts track the inheritance of traits across generations.

Evolution

• Evolution is the process of change in species over time, driven by mechanisms like natural selection.
• Natural selection: describes how organisms better adapted to their environment tend to survive and produce more offspring, passing on advantageous traits.
• Selective pressures: environmental factors influencing organism survival and reproduction.
• Adaptations: traits or characteristics that enhance survival in a specific environment.
• Convergent adaptations: unrelated species evolve similar traits due to similar environmental pressures.
• Divergent adaptations: related species evolve different traits due to differing environmental pressures and ecological niches.
• Speciation: the process by which new species originate from a common ancestor.
• The process of speciation involves variation, geographical or reproductive isolation, and the evolution of different adaptations.
• Theories of evolution explored: Lamarck's and Darwin's theories.

Fossils

• Fossils are remnants or traces of ancient organisms preserved in geological formations.
• Fossils provide evidence of past life forms and their characteristics, aiding in evolutionary studies and supporting the theory of evolution.
• Fossils reveal similar structures in different species, indicating common ancestry and evolutionary relationships, e.g. homologous structures.