LATG

Chapters 6 - 7

Cells & TissuesCells & Tissues

Organic Chemistry, Biochemistry Organic Chemistry, Biochemistry and Infectious Diseasesand Infectious Diseases

CellsCells

Prokaryotic = bacteria, blue-green algae

Eukaryotic = plants, animals, fungi, many unicellular organisms

Both cell types: have DNA, are membrane bound, haveribosomes, have similar basic metabolism

Eukaryotic cells: larger (~1000X), more complex DNA, have a nuclear and organelle membranes, have cytoskeleton

CellsCells

CellsCells

CellsCells

CellsCells

Plasma membrane: proteins and lipids that allows fat soluble molecules to penetrate easily but prohibits water soluble molecules from going across without facilitated diffusion or active transport

CellsCellsWithin the lipid bilayer are many types of proteins:cell receptors, transport proteins, enzymes

CellsCells

Lipid soluble substances can enter and leave the cellby passive diffusion following concentration gradients

CellsCells

Substances can also cross the membranes without energy expenditure via osmosis = solvent molecules (usually H20) move across a semi-permeable membrane due to osmotic pressure

Hypotonic Hypertonic Isotonic

CellsCellsFacilitated or carrier-mediated diffusion occurs with molecules that are not normally fat soluble, but become so when combined with a carrier substance allowing entry or exit from the cell

CellsCells

Active transport is the movement of substances against aconcentration or electrochemical gradient and usuallyrequires energy expenditure by the cell

CellsCells

CellsCells

Large molecules or entire cells can enter the host cell byendocytosis either via pinocytosis or phagocytosis and exitthe cell via exocytosis

CellsCellsThe nucleus is made up of DNA = deoxyribonucleic acid, and RNA = ribonucleic acid, and is involved in cell reproduction and metabolic activities

Nucleoli may be present in resting cells and are sites of ribosomal RNA production

The nucleus is surrounded by a nuclear membrane containing pores and continuous with the endoplasmic reticulum in some areas

CellsCellsDNA is made up of chains of nucleotides and form the basic element of genes which determine all of our inherited characteristics

Nucleotides consist of a sugar molecule = deoxyribose bonded with a phosphate group and a nitrogenous base

Nitrogenous bases can be either adenine, guanine, cytosine or thymine

CellsCellsDNA is usually found in double, complementary strands that are held together by hydrogen bonds between the nitrogenous bases

Adenine binds with thymine, cytosine binds with guanine

When the DNA is not replicating, these strands form a spiral or double helix

CellsCells

During DNAreplication, the complementary

strands separateand enzymes

known aspolymerases

add new basesthat are identical

to the originalopposite strand

CellsCellsAfter the DNA replicates itself, the cell is ready to divide. At this point there is condensing down of the DNA in the nucleus from the loosely arranged chromatin into distinct chromosomes.

CellsCellsMitosis, or cell division, produces two genetically identical cells

CellsCellsDNA replicates itself, but also can produce RNA in a process called transcription. The RNA leaves the nucleus as a single strand

DNA areas in the nucleolus produce ribosomal RNA or rRNA

Other RNA types are messenger (mRNA) and transfer (tRNA)

CellsCells

rRNA combines with proteins to form ribosomes

Ribosomes then ‘read’ the mRNA to synthesize proteinsfrom amino acids in a process called ‘translation’

CellsCells‘Translation’ uses rRNA, mRNA, and tRNA to createprotein molecules from amino acids

CellsCellsTranslation occurs on the surface of the endoplasmic reticulum, a membrane bound organelle in the cell’s cytoplasm

CellsCells

Electron microscope picturesshowing the rough ER andribosomes producing proteins

CellsCellsThere are other organelles found within the cytoplasm:

The Golgi apparatus is found close to the nucleus andendoplasmic reticulum. It’s job is to receive, sort and process the biomolecules it receives from the ER and resecrete them.

CellsCells

Mitochondria are used for aerobic respiration and productionof energy (ATP) for the for proper functioning of the cellsmetabolic processes.

CellsCells

Lysosomes are full of enzymes that break down fats, protein and carbohydrates into their smallest elements to be used by the mitochondria for energy.

Vacuoles are often found in the cytoplasm and assist ingetting rid of water and waste products from the cell

CellsCellsMicrotubules provide support for the cell known asthe cytoskeleton to help the cell keep its shape and control flow of elements through the cell.

Centrioles are bundles of microtubules thatassist in separation of the chromosomesduring mitosis when they form intomitotic spindles.

Microtubules also make up cilia and flagella that are hair-like surface projections used to move the cells themselves or material around the outside the cells.

TissuesTissuesCells bound together and serving a specific function are called tissues and include epithelium, connective tissue,muscle tissue, and nerve tissue.

Epithelium consists of sheets of cells that have a basal lamina and an unattached or free edge. It is typically found lining cavities, blood vessels, gland ducts and hollow organs.

TissuesTissues

Epithelium serves different functions depending on its typeand location but may be for protection, absorption, secretionor facilitate movement of substances over its free surface.

TissuesTissuesConnective tissue is found throughout the body and containsa variety of different cell types, depending on its location.

Dense and loose connective tissue contains fibroblasts and collagen fibers which provide elasticity to the tissue.

TissuesTissues

TissuesTissuesAdipose tissue contains adipocytes which store fat for metabolism and is primarily white. Brown fat is in many species but the greatest amount is found in species that hibernate and it is thought to have a role in maintaining body temperature by producing heat.

TissuesTissuesCartilage contains chondrocytes that are embedded in a semi-rigid matrix. The number of fibers and density of the matrix determines whether it is hyaline cartilage, elastic cartilage, or fibrocartilage.

TissuesTissuesBone is made up of osteocytes and ground substance that consists of calcium phosphate. The ends of long bones contain spongy or cancellous bone while the shaft is compact bone that surrounds the medullary cavity containing the bone marrow.

TissuesTissuesThe cells found within connective tissue can be fixed as seen with fibroblasts, chondrocytes, osteocytes, and adipose cells. They can also be wandering, usually coming from the blood, as seen with eosinophils, neutrophils, lymphocytes, monocytes, and mast cells.

TissuesTissuesMuscle cells can either be smooth or striated, depending on their function and appearance under a microscope. Smooth muscle is found in most of the our internal organs and exhibits involuntary rhythmic and tonic contractions.

TissuesTissues

Striated muscle can be either skeletal muscle, that contracts voluntarily, or cardiac muscle that contracts involuntarily.

TissuesTissuesNerve tissue is made up of neurons that are cells characterized by a nucleated cell body, dendrites, and an axon. Nerves respond to stimuli by polarizing and depolarizing by varying the concentration of sodium and potassium ions inside the cell.

TissuesTissuesMany nerves are covered with a myelin sheath that speeds the conduction of the impulses down the axon. The myelin is made from part of an oligodendrocyte cell that wraps around the axon and has gaps in it called nodes of Ranvier.

TissuesTissues

The axons end either in synapses with other nerve cells, or inmotor end plates, innervating muscle cells. The end releasesneurotransmitters which are chemicals that stimulate the nextnerve or muscle to respond.

Organic Chemistry, Organic Chemistry, Biochemistry and Biochemistry and

Infectious DiseasesInfectious Diseases

Chapter 7Chapter 7

BiochemistryBiochemistry

The study of chemistry within living The study of chemistry within living organismsorganisms Inorganic molecules-water, sodium, Inorganic molecules-water, sodium,

potassium, calcium--molecules without carbonpotassium, calcium--molecules without carbon Organic molecules-carbohydrates, lipids, Organic molecules-carbohydrates, lipids,

proteins--molecules with carbonproteins--molecules with carbon

CarbohydratesCarbohydrates

The sugar family of moleculesThe sugar family of molecules Found as mono-, di- and polysaccharidesFound as mono-, di- and polysaccharides Used as energy source, supportive Used as energy source, supportive

structures and nucleic acidsstructures and nucleic acids

MonosaccharidesMonosaccharides

Glucose--the most common simple sugar Glucose--the most common simple sugar found in biological systemsfound in biological systems Provides energy for all body systemsProvides energy for all body systems Only source of energy for central nervous Only source of energy for central nervous

systemsystem Galactose and fructose are other simple Galactose and fructose are other simple

sugars commonly foundsugars commonly found

DisaccharidesDisaccharides

Molecules made up of two simple sugarsMolecules made up of two simple sugars Sucrose, maltose and lactose are two Sucrose, maltose and lactose are two

commonly found disaccarhidescommonly found disaccarhides Both mono- and disaccharides are known Both mono- and disaccharides are known

as simple sugarsas simple sugars

PolysaccarhidesPolysaccarhides

Complex molecules made up of many Complex molecules made up of many (sometimes thousands) simple sugars(sometimes thousands) simple sugars

Starch, cellulose and glycogen are the Starch, cellulose and glycogen are the majors forms in animal and plant lifemajors forms in animal and plant life

Glycogen is the major storage form for Glycogen is the major storage form for sugars in the mammalian body, primarily sugars in the mammalian body, primarily in muscle and liverin muscle and liver

LipidsLipids

Fatty molecules with multiple functions Fatty molecules with multiple functions within the mammalian bodywithin the mammalian body Energy storageEnergy storage ProtectionProtection InsulationInsulation Cell membranesCell membranes

LipidsLipids

Major forms areMajor forms are Fatty acidsFatty acids TriglyceridesTriglycerides SteroidsSteroids

Fatty AcidsFatty Acids

The building blocks of most lipidsThe building blocks of most lipids Classified as saturated and unsaturated Classified as saturated and unsaturated

fatty acidsfatty acids Some of the unsaturated fatty acids are Some of the unsaturated fatty acids are

classified as essential--can not be made classified as essential--can not be made by the bodyby the body

TriglyceridesTriglycerides

Larger lipid molecule composed of three Larger lipid molecule composed of three fatty acids attached to one glycerol fatty acids attached to one glycerol moleculemolecule

Primary energy storage in the bodyPrimary energy storage in the body

SteroidsSteroids

Another type of lipid important in hormonal Another type of lipid important in hormonal balancebalance

Some steroidsSome steroids cholesterolcholesterol cortisolcortisol testosteronetestosterone estrogenestrogen Vitamin DVitamin D

ProteinsProteins

Made up of chains of amino acidsMade up of chains of amino acids Twenty amino acids are knownTwenty amino acids are known

Ten of these are essentialTen of these are essential These 20 amino acids combine to form These 20 amino acids combine to form

over 35,000 proteins during a mammal’s over 35,000 proteins during a mammal’s lifetimelifetime

Protein FunctionProtein Function

Structure--collagenStructure--collagen Enzymes--lipaseEnzymes--lipase Regulatory--G proteinsRegulatory--G proteins Transport--hemoglobinTransport--hemoglobin Protective--immunoglobulinsProtective--immunoglobulins Hormones--insulinHormones--insulin