CELLULAR ORGANIZATION

CELL THEORY

• All Living Things Are Composed of Cells

• Cells Are the Functional Unit of the Body

• Complementarity: Subcellular structures control biochemical activities

• Continuity of Life: Cells come from other cells

CELL DIVERSITY

• Human Body contains 50-106 trillion cells

• 200 different cell types

• Range from 2 micrometers to 1 meter in length

TYPICAL COMPOSITE CELL

• Cell membrane

• Nucleus

• Cytoplasm

• Organelles

CELL MEMBRANE

• Gives form to the cell, forms outermost limits of the cell

• Controls what enters and leaves the cell

• Selectively permeable

• FLUID MOSAIC MODEL–Phospholipid bilayer

–Proteins

LIPID BILAYER

• 2 Layers of phospholipids

–Heads

•Polar (charged)

•Hydrophilic

–Tails

•Nonpolar (uncharged)

•Hydrophobic

• Glycolipids - have attached sugar groups

PROTEINS - responsible for specialized functions

• Integral - embedded– Channels / Pores

– Transporters / Carriers

– Receptors

• Peripheral - attached– Enzymes

– Glycocalyx - “sugar coating”

– Cell ID markers

NUCLEUS• Cell control center- directs activities

• Bounded by a double membrane, the nuclear envelope

• Contains genetic information (DNA) in the form of genes

• Nucleolus - site of ribosome assembly

• Multinucleate - many nuclei

• Anucleate - no nucleus

CYTOPLASM

• Cell forming material–cytosol - viscous transparent fluid

–cytoplasmic organelles - “little organs”

–inclusions - chemical substances that may be stored in the cytoplasm

ORGANELLES• Endoplasmic reticulum

– rough ER - transport & membrane synthesis

– smooth ER - lipid synthesis & drug detoxification

• Ribosome - synthesize proteins

• Golgi apparatus - series of flattened membrane sacs that process, sort and modify proteins and lipids for export or cell use

ORGANELLES• Mitochondria - ATP formation

• Lysosome - contains hydrolytic enzymes to break down molecules, digest bacteria

• Microtubules / Microfilaments - form part of the cytoskeleton that serve as support structures and assist with cell movement

–Cilia -numerous, short, transport substnces across the membrane

–Flagella - often single, propels the cell

ORGANELLES

• Peroxisomes - contain enzymes that oxidize toxic substances (neutralize free radicals)

• Centrosomes/centrioles - function in cell division

• Storage organelles - Vacuoles, Vesicles, may contain:–fats, oils, melanin

CELL PHYSIOLOGY

Membrane Transport

PASSIVE PROCESSES

• Do not require energy–simple diffusion

–facilitated diffusion

–osmosis• isotonic

•hypotonic

•hypertonic

– bulk flow/filtration

ACTIVE PROCESSES• REQUIRE ENERGY / ATP

• Goes against the concentration gradient–active transport using carrier proteins

–vesicular transport

•endocytosis - phagocytosis

pinocytosis

•exocytosis - cell export

Source of Cell Energy ATP Catabolism

• Adenosine triphosphate (ATP)

• ATP - 5 carbon sugar (ribose)

nitrogen containing base (adenine)

3 phosphate groups

• ATP---P ~ P ~ P

• ATP---ADP + P + Energy

CELL DIVISION• Process by which a cell reproduces itself

• Nuclear division - mitosis, meiosis

–Mitosis - somatic cell division in which the cell retains the same number of chromosomes

–Meiosis - reductional division in which the chromosome number is reduced

• Cytoplasmic division - cytokinesis

CELL CYCLE

• Growth Phase 1 - synthesis of lipids, proteins and carbohydrates

• S Phase - DNA synthesis

• Growth Phase 2 - formation of spindle fibers for cell division, centrioles divide

• Mitosis / Meiosis

• INTERPHASE

STAGES OF MITOSISPROPHASE

METAPHASEANAPHASE

TELOPHASE

PROPHASE

• Chromatin condenses into chromosomes

• Spindle Fibers appear

• Nuclear membrane disappears

• Nucleolus disappears

• Centrioles move to opposite poles

• Chromosomes begins to migrate toward equator

METAPHASE / ANAPHASE

• Chromosomes line up along equator

• centromere of each pair attached to a spindle fiber

• Centromeres split; sister chromatids separate

• Chromatids migrate to opposite poles

TELOPHASE & CYTOKINESIS

• Opposite of Prophase

• Chromosomes elongate forming indistinct chromatin

• Nuclear membrane reappears

• Nuclear reorganization occurs

• Two new daughter cells formed

NUCLEIC ACID STRUCTURE

DNA - forms genetic code

RNA - functions in the process of protein synthesis

DNA - DEOXYRIBONUCLEIC ACID

• Double stranded helix; nucleus

• Contains: 5 carbon sugar, phosphate group, nitrogenous base

• Nitrogenous bases–adenine-thymine

–cytosine- guanine

• Base pairing occurs

DNA RELICATION

• DNA makes an exact duplicate of itself

• DNA strands separate into separate strands and each one is used as a template for a new strand of nucleotides

• Two double- helix molecules are formed, each contains an original strand and a newly synthesized strand

RNARIBONUCLEIC ACID

• Single stranded

• Uracil substitutes for thymine

• consists of 5 carbon sugar ribose, phosphate group, nitrogenous base

• Bases: adenine, guanine, cytosine, uracil

• RNA types: mRNA, tRNA, rRNA

GENETIC CODE

What are genes?

GENE

• Is a segment of a DNA molecule that may consist of 1,000 pairs of nucleotides that code for a specific protein

• ONE GENE=ONE POLYPEPTIDE=ONE PROTEIN

AMINO ACIDS

• Each amino acid is coded for by a triplet of bases

• Codon - triplet of bases that codes for a single amino acid

TRANSCRIPTIONRNA SYNTHESIS

• mRNA is synthesized using a DNA molecule as a template

• mRNA carries MESSAGE out of the nucleus to the ribsome in the cytoplasm

TRANSLATIONPROTEIN SYNTHESIS

• Genetic code is translated forming a specific sequence of amino acids

• mRNA attaches to ribosomes in cytoplasm

• tRNA molecules bring specific A.A. to the ribosome for placement in the dictated sequence

• Ribosome bonds amino acids together to form proteins / polypeptides

• Protein is released

Cell Aging

• Wear & Tear Theory - cell damage by chemicals and free radicals have cumulative effect

• Immune Theory - weakening of immune response or auto-immune disorders

• Genetic Theory - “Telomere Clock”

– Telomere = string of nucleotides on the end of chromosomes; (TTAGGG) repeated >1000X

– 50-100 nucleotides lost each division.