CELLS – Chapters 6, 7, 11, 12 Cell Structure, Membrane Function, Cell Communication and the Cell Cycle/Mitosis

CELLS are based on Cell Theory states that 1. all living things are made of cells 2. all cells come from other cells 3. Cells are the most basic unit of life Cell structures & function Cell replication Ch 6, 7, 11 Ch 12

Endomembrane System Secreted or membrane- bound proteins only (Free ribosomes synthesis soluble cytosolic proteins)

Cells are dynamic! Cell division & growth Metabolism – Building proteins and other cell parts (anabolism) – Catabolism – Repair of damaged cell parts – Chemical reactions to stay alive and maintain homeostasis Cell communication

Membrane Structure & Function

Critical components of selectively permeable membrane Phospholipids – barrier Cholesterol – regulates fluidity Transmembrane proteins – render selectivity – Receptors – Ion channels – Aquaporins – allow water to pass into/out of cell – Transport proteins Outer leaflet – Carbohydrates – cell identification – Extracellular matrix (ECM) – interaction with surroundings

Types of molecular movement across the cell membrane Passive Transport – Diffusion – Facilitated Diffusion – Osmosis Active Transport Bulk transport: Endocytosis/Exocytosis/Pinocytosis

Terms to know: Concentration gradient – a form of stored energy Solute Solvent Isotonic Hypertonic Hypotonic Equilibrium

Phrases to know Passive transport – Molecules move down/with their concentration gradient – From high concentration to low concentration Active transport – Molecules move against their concentration gradient – From low concentration to high concentration – Requires input of ATP energy from cell

Passive transport - Diffusion In the absence of any partitions, molecules will move from an area of high concentration to an area of low concentration

Diffusion across a cell membrane What types of molecules can cross the membrane barrier freely? Molecules of dyeMembrane (a) Passive transport of one type of molecule Equilibrium (b) Passive transport of two types of molecules Equilibrium mcgraw- hill.com/sites/ /stude nt_view0/chapte r2/animation__h ow_diffusion_wo rks.htmlhighered. mcgraw- hill.com/sites/ /stude nt_view0/chapte r2/animation

Passive transport - Facilitated Diffusion Requires a protein channel

Passive transport - Osmosis Movement of H2O through aquaporin proteins Depends on water potential – the direction water molecules will flow is determined by solute concentration on either side of the membrane

Remember secondary and tertiary structure???

Animal cell Normal Lysing Plasmolysis Plant cell Flaccid Flaccid (wilts) Turgid Turgid (normal) Plasma membrane (a) Isotonic solution(b) Hypotonic solution(c) Hypertonic solution Shriveled The effects of osmosis differ in plant and animal cells

Active Transport Moves solutes against their concentration gradient via a transport protein

Active transport – bulk transport via exocytosis, endocytosis & pinocytosis hill.com/sites/ /student_view0/chapter2/animation__phagocytosis.html

Receptor-mediated endocytosis

Receptor-mediated endocytosis: cholesterol uptake /content/chp05/ html

Visual Summary 5.2

Cell Signaling Cells communicate with one another for several reasons – Growth – Development – Stimulate immune response – Regulate gene expression – Relay/transmit signals in nervous system – Fight or flight response – Homeostasis (example: regulate blood glucose)

Three stages of cell signaling Reception, Transduction, Response Animations: Ch 11 hill.com/sites/ /student_view0/chapter2/animation__receptors_linked_to_a_ch annel_protein.html

Ch 12 – Mitosis & the Cell Cycle

Mitosis: duplicating cells Occurs in somatic cells (body cells) throughout life – Wound healing – Growth – Repair/maintenance (skin, intestine, hair follicles, replacement of uterine lining after menstruation)

Results of (normal) Mitosis 2 genetically identical cells (“daughter cells”) hill.com/sites/ /stude nt_view0/chapter2/animation__ mitosis_and_cytokinesis.html

Checkpoints regulate the cell cycle

Interplay of Cyclin and Cdk proteins regulates progression through the cell cycle

Normal cell division has 2 key characteristics: Density-dependent inhibition Anchorage dependency Cells that are not adhered to a surface will not proliferate Cells use cell signaling to detect growth factors and density signals