Cell stuff etc

MODERN CELL THEORY

• The cell is the most basic unit of life

• All organisms are made of cells

• All cells arise from other cells

• All cells have similar biomolecules and biochemical reactions

• All cells contain genetic material which is passed from one cell to another

• All chemical and physiological processes in the body happen in the cell

BIOMOLECULES

Molecule produced by living organism

Carbohydrate

Made of: Monosaccharides (ex starch, cellulose)

Protein

Made of: Amino acids (ex enzymes, hormones)

Lipid

Made of: Fatty acids, glycerol (ex steroids, fats)

Nucleic acid

Made of: Nucleotides → made of nitrogenous base, pentose/five-carbon sugar (sugar backbone), >=1 phosphate group

Nucleic acid: DNA (Deoxyribonucleic acid)

Nitrogenous base pairing: Adenine-Thymine (A-T), Cytosine-Guanine (C-G) → purine: adenine, guanine ; pyrimidine: thymine, cytosine

Sugar backbone: Deoxyribose

Double strands

Nucleic acid: RNA (Ribonucleic acid)

Nitrogenous base pairing: Adenine-Uracil (A-U), Cytosine-Guanine (C-G) → purine: adenine, guanine ; pyrimidine: uracil, cytosine

Sugar backbone: Ribose

Single strand

TYPES OF CELLS

Cell type

Prokaryote

• No true nucleus

• No membrane-bound organelles

• Mostly unicellular

• Kingdoms: Archaea, Bacteria

• Unique organelles: Nucleoid region, capsule, plasmid (extra circular DNA), pilli

Eukaryote

• True nucleus

• Membrane-bound organelles

• Unicellular, multi

• Kingdoms: Animalia, Plantae, Fungi, Protista

• Organelles also present in prokaryotes: Ribosomes, cytoplasm, cell membrane, genetic material

ORGANELLE

Cell organs

Cell membrane

Cell communication and transportation

Genetic material

Store genetic info

Ribosomes

Protein synthesis

Nucleus

Command center

Golgi apparatus

Transpo of proteins and other cellular components

Endoplasmic reticulum

Protein synthesis and lipid production

Mitochondria

ATP synthesis

Vacuole

Storage of food and other cellular components (does lysosome’s job for plants)

Chloroplast

Plant cell specific: Photosynthesis

Cell wall

Plant cell specific: Structural support, protection, control cell transpo

Plasmodesmata

Plant cell specific: channel through the plant cell wall that allows molecules and substances to move in and out of the cell

Lysosome

Animal cell specific: Cellular digestion

Centriole

Animal cell specific: Production of spindle fibers during cell division

CELL DIVISION

How parent cell divides into daughter cells

Either mitosis (exact replicas) or meiosis (reproduction: needs fertilization)

Mitosis

• Equational division

• Diploid (2n) → diploid (2n) (always 2 copies of each/sets of chromosomes)

• 2 daughter cells

• Produces somatic or body cells

• For growth and repair

• Stages: Prophase, metaphase, anaphase, telophase

Mitosis stage: Prophase

Chromosomes become distinct in diploid cell

Mitosis stage: Metaphase

Chromosomes line up

Mitosis stage: Anaphase

Sister chromatids head towards opposite poles

Mitosis stage: Telophase

Cell splits = 2 diploid cells

Meiosis

• Reductional division

• Diploid (2n) → haploid (n) (1 copy of each chromosome)

• 4 daughter cells

• Produces sex cells or gametes

• For reproduction

• Stages: Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II

Meiosis stage: Prophase I

Chromosomes become distinct

Meiosis stage: Metaphase I

Chromosomes line up by pairs

Meiosis stage: Anaphase I

Chromosome pairs move towards opposite poles

Meiosis stage: Telophase I

Cell splits = 2 haploid cells

Meiosis stage: Prophase II

2 haploid cells ready for division

Meiosis stage: Metaphase II

Chromosomes line up

Meiosis stage: Anaphase II

Sister chromatids go towards opposite poles

Meiosis stage: Telophase II

Each cell splits = 4 haploid cells

DEVELOPMENT OF GAMETES

Development of sex cells, mix of mitosis and meiosis

Development of male gametes in angiosperms

1. Microsporocyte (pollen mother cell) 2n

→ Microsporogenesis (meiosis) →

2. 4 Microspores n

→ Microgametogenesis (meiosis) →

3. Microgametophyte (tricellular pollen) n

Development of female gametes in angiosperms

1. Megasporocyte (megaspore mother cell) 2n

→ Megasporogenesis (meiosis) →

2. Megaspore n

→ Megagametogenesis (mitosis) →

3. Megagametophyte (embryo sac) n

Spermatogenesis - development of sperm

1. Spermatogonium (2n)

2. Primary spermatocyte (2n)

→ Meiosis (stage I) →

3. 2 secondary spermatocyte (n) each

→ Meiosis (stage II) →

4. 2 spermatids (n) each

5. 1 sperm (n) each

Oogenesis - development of egg

1. Oogonium (2n)

2. Primary oocyte (2n)

→ Meiosis (I) →

3. Secondary oocyte (n), Primary polar body (n)

→ Meiosis (II) →

4. Egg (n), Polar bodies (n) (will disintegrate)

METABOLISM

Refers to all chemical reactions of cell → Anabolism (build up, synthesize), Catabolism (break down)

Proteins, fats, polysaccharides -catabolism→ ←anabolism- amino acids, fatty acids and glycerol, glucose

Photosynthesis

Anabolic

Stages: Light-dependent reactions, light-independent reactions/Calvin Cycle

Photosynthesis stage: Light-dependent reactions

Conversion of light energy and water to chemical energy and oxygen (H2O → O2)

Photosynthesis stage: Light-independent reactions/Calvin Cycle

Using chemical energy from previous stage: Formation of carbohydrate molecules from carbon dioxide (CO2 → C6H12O6)

Respiration

Catabolic: Using glucose to produce ATP (Adenosine triphosphate) (main energy carrying molecule used by all cells, necessary in all functions)

Glucose, ATP, NAD+ → ATP, H2O

Stages: Glucolysis, Oxidation of pyruvate, Citric Acid/TCA/Krebs Cycle, Oxidative Phosphorylation

Respiration stage: Glucolysis

Conversion: glucose → pyruvate

Respiration stage: Oxidation of pyruvate

Conversion: pyruvate → acetyl CoA

Respiration stage: Citric Acid/TCA/Krebs Cycle

10-step cycle: Produces oxaloacetate from acetyl CoA = ATPs, NADHs, FADH2

OR if no oxygen: Fermentation - anaerobic respiration

1. Lactic acid fermentation - convert: glucose → lactic acid (C3H6O3)

2. Ethanol fermentation - convert: glucose → ethyl alcohol (C2H5OH)

Respiration stage: Oxidative phosphorylation

Electron transport chain and chemiosmosis: synthesis of ATPs using ATP synthase

CELLULAR TRANSPORT

How cells move substances (molecules, ions) across/within cells

Passive transport

Move molecules w/o energy

• Diffusion, osmosis

Passive transport: Diffusion

• No semi-permeable membrane

• Movement of any particle

• High to low solute concentration

Passive transport: Osmosis

• Across semi-permeable membrane

• Movement of solvent (solute can’t pass through membrane)

• Low to high solute concentration

Active transport

Uses ATP (energy) to move molecules

• eg Phagocytosis (cell-eating, engulf large particles like bacteria foreign particles), pinocytosis (cell-drinking, absorb extracellular fluids and dissolved solutes or nutrients), uptake of glucose in intestine

GENETICS

Study of genes

Allele

Gene form for certain trait (eg red and white alleles for flower color)

Homozygous

Purebred: Having 2 of same allele

Heterozygous

Half-bred: Having 2 diff alleles for certain trait

Recessive

Hidden or masked gene

Dominant

Expresses gene

Phenotype

Organism’s physical characteristics

Genotype

Organism’s actual genetic composition

Common cross: Heterozygous x homozygous recessive

= phenotype ratio 1 dominant:1 recessive

Common cross: Heterozygous x heterozygous

= phenotype ratio 3 dominant: 1 recessive

DNA DOUBLE HELIX STRUCTURE

Adenine-Thymine (A-T) and Cytosine-Guanine (C-T) base pairings

CENTRAL DOGMA OF MOLECULAR GENETICS

Process in which information in DNA is converted into functional product: Shows flow of genetic information (info in DNA is crucial for all proteins, RNA acts as messenger)

Replication

DNA → DNA

DNA double chain unzips = new complementary strand per unzipped strand = 2 complete double-chains

Transcription

DNA → RNA

A-T → A-U (uracil) base pairing

Translation

RNA → Protein

Messenger RNA from transcription used as template for synthesis of amino acids (3 base codes per amino acid)

One Gene-One Enzyme Hypothesis

Each gene in organism’s genome is responsible for the encoding of a single, specific enzyme that regulates a specific step in the metabolic pathway