Cell Structure
Membranes
Functions
Divide cell into compartments
Surfaces that hold enzymes
Regulate passage of molecules in/out of cells/organelles #
Composition
Monolayer or bilayer
Hydrophilic backbone (glycerol and phosphate)
Hydrophobic tail (fatty acid)
Proteins
~60% of the membrane
Extrinsic: large hydrophilic regions
Intrinsic: large hydrophobic regions
Plus oligosaccharides = glycoproteins #
Plus oligosaccharides: glycolipids
Properties
Can grow by fusing vesicles
Exocytosis: using vesicles to excrete materials out the surface membrane to the exterior #
Endocytosis: invagination of outer membrane containing materials needed for the cell
Selectively permeable: certain materials cross membrane easier than others
More permeable to hydrophobic substances
Causes need for facilitated diffusion
EX: inorganic salts, sugars, amino acids
Movement of charged particles
Active transport: membrane protein uses energy and solute concentration to change shape and pump molecules across
Constantly changing, dynamic based on needs of cell
Cell Characteristics
Prokaryotic
Eukaryotic
No membrane bound organelles; nucleus, mitochondria, ER, golgi, etc.
Simpler; most archaic line of evolution
Bacteria and Archaea
Plants, animals, fungi, protists
Has membrane bound nucleus #
Presence of organelles
Unicellular Organisms - composed of a single cell
Multicellular Organisms - composed of multiple cells
No division of labor; cell must perform all tasks
Division of labor; more efficient; specialization given to organelles #
Organelles
Plant Cells Only
Animal and Plant Cells
Animal Cells Only
Lysosomes: contain digestive enzymes, recycles components
Cell round shape
Glyoxysomes: convert stored fats into sugars
Plastids #
Cell rectangular shape
Central Vacuole: membrane bound (tonoplast) which stores water, calcium, potassium, pigments, metabolic wastes, etc. #
Amyloplasts: store starch
Chromoplasts: store red or yellow pigment for flowers and fruits
Proplastids: young, meristematic cells
Leucoplasts: colorless plastids
Chloroplasts: chlorophyll rich, carries out photosynthesis, has own DNA
Thykaloids:photosynthetic membrane
Granum: flat vesicles, staked, carry out chemiosmotic phosphorylation
Aids in cell growth, larger it gets
Protoplasm: all substance of cell, not including cell wall
Nucleus: houses DNA
Plasma Membrane: semipermeable membrane that surrounds protoplasm
Cytosol: liquid substance of protoplasm, not including organelles
Cytoplasm: protoplasm, includes nucleus, vacuoles, and cytoplasm
Central Dogma: DNA --> RNA --> Protein
Nuclear Envelope: inner and outer membrane surrounding nucleus
Nuclear Pores: in envelope, transport materials between nucleus and cytoplasm
Nucleoplasm: substance inside nucleus, includes DNA, histones, RNA, enzymes, nucleic acids, and water
Nucleoli: synthesize ribosomal RNAs
Ribosomes:protein synthesis
Mitochondria: aerobic respiration, ATP synthesis
Crista: folds on inner membrane
Matrix: liquid in between crista and membranes
Has own DNA #
Endoplasmic Reticulum
Peroxisomes: breaks down hydrogen peroxide into water and oxygen
Smooth: lipid synthesis
Rough: ribosomes attached, protein synthesis
Golgi apparatus: collection of dictyosomes, packages materials for transportation
Cytoskeleton
Microtubules: reinforcement of cell shape, helps motility
Composed of;
Examples;
Beta-tubulin: polymerize into tublin
Centrioles: organizes the microtubules of flagella
Alpha-tubulin: polymerize into tubulin
Cilia: used for movement, similar to flagella, only shorter
Flagella: used for locomotion, sperm cells
9+2 arrangement of microtubules in cilia and flagella:
Basal Body: similar to centrioles #
Microfilaments: actin, movement of organelles other than flagella, cilia, and chromosomes
Cell Wall: plant cells only, layer outside for plasma membrane #
Hemicelluloses: polysaccharides that crosslink cellulose molecules
Primary Cell Wall: plant cells, during division, thin
Microfibril: crystallized cellulose
Secondary Cell Wall: sclerenchyma cells, after division, interior to primary, contains lignin
Fungal cells: do not have cellulose in cell wall, but chitlin, do not contain plastids #