BIOL 251 Exam 1

Cell theory

• All living things are composed of cells

• The cell is the basic unit of life

• All cells come from pre-existing cells

Prokaryotes

• All bacteria and archaea

• appeared ~4.5 bya

• Have DNA but no nucleus

• No membrane enclosed internal structures

• Divide in as little as 20 minutes

Eukaryotes

• Appeared ~1.5 bya

• Store DNA in the nucleus

• Contain membrane enclosed organelles

Viruses

• Not living

• Assembly of molecules

• live as parasites in host cells

• Replicate inside cells

Both prokaryotes and eukaryotes

• Plasma membrane

• Cytosol

• Ribosomes

• Cytoskeleton

• DNA

Plasma membrane

• Maintains intracellular conditions

• Controls IN/OUT

Cytosol

• Regions not enclosed in intracellular membranes

• Crowded with molecules

Ribosomes

• Site of protein synthesis

• Consists of large and small subunits

Cytoskeleton

• Protein fibers that give shape and structure

• Helps with cell, organelle, and vesicle movement

DNA

• Carrier of hereditary information

• Nucleotides are the building blocks

• Double stranded

• H-bonds between bases (A and T, C and G)

• Antiparallel

Membrane enclosed organelles

• Only found in eukaryotic cells

• Nucleus

• Mitochondria

• Chloroplasts

• Endoplasmic reticulum (ER)

• Golgi apparatus

• Lysosome

• Peroxisome

Nucleus

• DNA storage

• Site of DNA replication and transcription

Mitochondria

• Produces energy for the cell

• Originated from aerobic bacteria that were engulfed by a eukaryotic cell

Chloroplasts

• Perform photosynthesis

• Found in plants and algae

• Originated from a photosynthetic bacteria

Endoplasmic reticulum

• Can be rough (with ribosomes) or smooth (no ribosomes)

• Smooth is site of molecule biosynthesis, regulation of calcium concentration, and detoxification

Golgi apparatus

• Stack of membranous stacks

• Site of modification and sorting of proteins

• Proteins get in and out via vesicles

Lysosome

• Site of macromolecule digestion

• Acidic, enzyme filled compartments

Peroxisome

• Site of oxidation reduction

• Break down fatty acids

• Synthesis of plasmogens

Covalent bond

• Electrons are shared by two atoms

• The strongest type of bonds in human bodies

Polar covalent bond

Unequal charge distribution

Nonpolar covalent bond

Equal charge distribution

Electrostatic interaction

Ionic bonding, hydrogen bonding, Van der Waals interaction

Ionic bond

Fully charged attraction

Hydrogen bond

Sharing of an electropositive hydrogen by two electronegative atoms

Van der Waals Interaction

Atoms show a weak interaction with each other due to fluctuating electrical charges (dipoles)

Hydrophobic forces

Water forces hydrophobic molecules together to minimize disruption of H-bonding between water molecules

Acids

Donate protons

Bases

Accept protons

Monosaccharides

Composed of C, H, O (CH₂O)_n, where n=3 to 8

Isomers

Molecules composed of the same atoms but having different arrangements

Condensation reaction

Consumes energy, water is expelled

Hydrolysis reaction

Releases energy, water is consumed

Polysaccharides

• Starch

• Glycogen

• Cellulose

Starch

• How plants store glucose

• Moderate branching

• Alpha glycosidic bonds

Glycogen

• How animals store glucose

• Extensive branching

• Alpha glycosidic bonds

Cellulose

• Found in plant cell walls

• No branching

• Beta glycosidic bonds (humans lack the enzyme to break these bonds)

Oligosaccharides

• Short chain of monosaccharides (3 - 10)

• Used as modifications in glycoproteins and glycolipids (found in cell membranes and selectively recognized by other cells)

Fatty acids

• Lipid building blocks

• Carboxyl group and hydrocarbon chain

Saturated fatty acids

No double bonds, saturated with hydrogens

Unsaturated fatty acids

Double bonds prevent maximum hydrogen saturation

Triacylglycerol

• Storage molecule for fatty acids

• Contains one glycerol and three fatty acids

• Bonds with the COOH of fatty acids → ester bonds

Phospholipids

Phosphoglycerides + sphingolipids (no glycerol)

Membrane lipids

• Phosphoglyceride components - glycerol, 2 fatty acids, and a polar head group

• Ampiphatic

• Form bilayers

Ampiphatic

Hydrophilic portion + hydrophobic portion

Steroids

• Four ring structure

• Function as membrane components and hormones

Amino acids

• Form chains called polypeptides

• Central carbon bonded to an amino group and a carboxyl group

• Characterized by side chain (R group)

Peptide bond

Linkage between 2 amino acids

Nucleic acids

Nucleotide building blocks

Nucleotide

Five carbon sugar, phosphate group, nitrogenous base

Nitrogenous bases

Pyrimidines (1 ring - cytosine, thymine, gunaine) + puridines (2 rings - adenine, guanine)

Phosphodiester bond

Between the phosphate group of one nucleotide and the hydroxyl group of another

RNA

Single stranded - (A, U, C, G)

ATP

Energy stored in phosphoanhydride bonds (break to release)

Endosymbiosis

• Two independent membranes

• Independent DNA genome