Cell Biology: Cell Structure

Cell Biology

Cell Structure

• Plasma membrane: semi-permeable membrane separating cell from environment
• Cytoplasm: jelly-like substance inside cell where metabolic reactions occur
• Nucleus: contains genetic material (DNA)
• Mitochondria: site of cellular respiration (energy production)
• Endoplasmic reticulum (ER): involved in protein synthesis and transport
• Ribosomes: site of protein synthesis
• Lysosomes: contain digestive enzymes for cellular recycling

Cellular Processes

• Photosynthesis: process by which cells convert light energy into chemical energy
• Cellular respiration: process by which cells generate energy from glucose
• Mitosis: process of cell division resulting in two identical daughter cells
• Meiosis: process of cell division resulting in four non-identical daughter cells (gametes)

Genetics

Mendelian Genetics

• Laws of inheritance: segregation, independent assortment, and dominance
• Genotype: genetic makeup of an individual
• Phenotype: physical expression of genotype
• Dominant and recessive alleles: determine trait expression
• Punnett squares: tool for predicting offspring genotypes and phenotypes

Molecular Genetics

• DNA structure: double helix with sugar-phosphate backbone and nitrogenous bases
• DNA replication: process of creating identical copies of DNA
• Transcription: process of creating RNA from DNA template
• Translation: process of creating protein from RNA sequence
• Mutations: changes in DNA sequence affecting gene function

Evolution

Mechanisms of Evolution

• Natural selection: process by which populations adapt to environment
• Genetic drift: random change in allele frequency
• Mutation: change in DNA sequence
• Gene flow: movement of genes between populations

Evidence for Evolution

• Fossil record: chronological record of life on Earth
• Comparative anatomy: similarities and differences between species
• Molecular biology: similarities and differences between DNA and protein sequences
• Biogeography: geographic distribution of species

Evolutionary Processes

• Speciation: process by which new species emerge
• Adaptation: process by which populations adapt to environment
• Co-evolution: process by which species evolve in response to each other
• Macroevolution: large-scale evolutionary changes over time

Cell Biology

Cell Structure

• Plasma membrane separates cell from environment and regulates what enters and leaves
• Cytoplasm is a jelly-like substance inside the cell where metabolic reactions occur
• Nucleus contains most of the cell's genetic material in the form of DNA
• Mitochondria are the site of cellular respiration, generating energy for the cell
• Endoplasmic reticulum (ER) is involved in protein synthesis and transport, and has two types: rough ER (with ribosomes) and smooth ER (without ribosomes)
• Ribosomes are small organelles found throughout the cytoplasm, responsible for protein synthesis
• Lysosomes contain digestive enzymes for cellular recycling and maintenance

Cellular Processes

• Photosynthesis converts light energy into chemical energy, occurring in chloroplasts
• Cellular respiration generates energy from glucose, occurring in mitochondria
• Mitosis is the process of cell division resulting in two identical daughter cells, with four stages: prophase, metaphase, anaphase, and telophase
• Meiosis is the process of cell division resulting in four non-identical daughter cells (gametes), with two successive cell divisions and crossover

Genetics

Mendelian Genetics

• The law of segregation states that each pair of alleles separates during gamete formation
• The law of independent assortment states that alleles for different genes are sorted independently
• The law of dominance states that one allele can be dominant over another
• Genotype is the genetic makeup of an individual, determined by alleles
• Phenotype is the physical expression of the genotype, determined by environment and genotype
• Dominant and recessive alleles determine trait expression, with dominant alleles masking recessive alleles
• Punnett squares predict offspring genotypes and phenotypes by crossing probablility

Molecular Genetics

• DNA structure consists of a double helix with a sugar-phosphate backbone and nitrogenous bases
• DNA replication creates identical copies of DNA, occurring in S phase of the cell cycle
• Transcription creates RNA from a DNA template, occurring in the nucleus
• Translation creates protein from an RNA sequence, occurring in the cytoplasm
• Mutations change the DNA sequence, affecting gene function and potentially leading to genetic disorders

Evolution

Mechanisms of Evolution

• Natural selection adapts populations to their environment through differential reproduction
• Genetic drift randomly changes allele frequency, often in small populations
• Mutation changes the DNA sequence, potentially affecting gene function
• Gene flow moves genes between populations, increasing gene variation

Evidence for Evolution

• The fossil record provides a chronological record of life on Earth
• Comparative anatomy shows similarities and differences between species
• Molecular biology compares DNA and protein sequences between species
• Biogeography studies the geographic distribution of species, showing patterns of evolution

Evolutionary Processes

• Speciation is the process by which new species emerge, often through geographic isolation
• Adaptation enables populations to adapt to their environment
• Co-evolution occurs when species evolve in response to each other
• Macroevolution refers to large-scale evolutionary changes over time, shaping the diversity of life on Earth

Learn about the different components of cell structure, including the plasma membrane, cytoplasm, nucleus, mitochondria, endoplasmic reticulum, ribosomes, and lysosomes.