ANSC 360 Quiz 1 - Cells and Tissues

Who had the first coherent theory of cellular function

Theodor Schwann - 1839 - first coherent theory of cellular function as basis for all life

Are viruses alive

NO

Prokaryotic

Pro = before, karyos = nucleus

No membrane bound organelles or nucleus

Bacteria/archaea

Eukaryotic

Eu = good, karyos = nucleus

Nucleus with genetic material, remainder of cell is the cytoplasm with membrane-bound organelles

Animals, plants, algae, yeasts, etc

Do red blood cells have a nucleus

No, they lose it when they mature

Do muscles cells have a nucleus

Yes, they have multiple by the time they mature

Benefits of compartmentalization in eukaryotes

Greater control over genetic expression

Separation of self-destructive enzymes from remainder of the cell

Isolates proteins for export from internal ones

Cell membrane

Most important cellular structure

Not a passive barrier

Controls what passes between the cytosol and interstitial fluids

Nucleus

Spherical shape bound by a nuclear membrane, with a double-walled membrane with pores that control the passage of mRNA out of the nucleus

Maintains hereditary continuity and directs cell function by controlling protein synthesis

Carries out rRNA synthesis and holds enzymes for RNA and DNA synthesis

Proteins of the nucleus

Chromatin

Histones

Chromatin

Important during mitosis!!!

Euchromatin = active genes

Heterochromatin = inactive, dark and danse when viewed

Histones

Most conserved of all animal proteins

Holds DNA in place to protect it

Cytoplasmic inclusions

Glycogen granules

Lipid droplets

Adipocytes

Glycogen granules

Concentrations of animal starch aka carbs for future energy

ONLY in muscle or liver cells

Lipid droplets

Concentrations of triglycerides or neutral fats

Large lipid droplets in most cells indicate impending apoptosis

Adipocytes

Fat cells - large lipid droplet with small cytoplasm ring

Apoptosis

Cell death

Cytoplasmic organelles

Distinct structures with some cellular function and most are separated from cytoplasm by a membrane

Lysosomes

Catabolic enzymes (acid hydrolases) to destroy pathogens, nutrient processing (TG into FA and glycerol), and cell component recycling

Membranes protect the rest of the cell

Important in autolysis - self-destruction and apoptosis (ability lost in cancer cells)

Peroxisomes

Similar to lysosomes but calmer - destroys things via emulsion

Mitochondria

ENERGY!!!

Internal space = matrix for citric acid and FA oxidation enzymes

Inner membrane folds = cristae - electron transport enzymes

Inter-membrane space - enzymes for ATP synthesis

Outer membrane - control of metabolite passage

What else is special about mitochondria?

Used to be a separate, symbiotic organism

Only passed down through the mother’s lineage

Endoplasmic reticulum appearance

Layered sheets of membranes like a Danish pastry

Smooth ER

Lipid synthesis

Steroid synthesis

Glycogen synthesis

Ca flux in muscles (sarcoplasmic reticulum)

Rough ER

Ribosomes attached to surface

Synthesizes proteins for export

Protein also accumulates in the RER

Golgi Apparatus

Receives transport vesicles carrying proteins for export from RER

Processes secretory proteins (adds lipids/carbs to AA chains or clips AA chains)

Releases secretory vesicles - travels to plasma membrane to release proteins to exterior

Membrane recycling process

Done by Golgi Apparatus

protein synth.=> RER pinches off -- transport vesicle => Golgi => pinches off -- secretory vesicle => plasma membrane -- protein released

Nonmembranous organelles

Ribosomes

Cytoskeleton

Ribosomes

Non membranous organelles

Synthesizes proteins!!!

Translate mRNA into polypeptide chains

Attaches to ER for export production, like Islet cells in pancreas for insulin

Some are free in cytoplasm for proteins for intracellular use

Cytoplasm vs cytosol

Cytosol = liquid

Cytoplasm = liquid + organelles (minus nucleus)

Cytoskeleton

Non-membranous organelle

Provides framework/strength for cell

Hold organelles in place

Transports materials by creating railroad tracks with microtubule tracks

Links cells together

Made of protein fibers (3 types)

Three types of proteins in cytoskeleton

Microfilaments

Intermediate fibers

Microtubules

Microfilaments

Actin (contractile protein in muscle)

Used for cleavage during telophase of cell division

Intermediate fibers

Various proteins

Most stable part of the cytoskeleton

Gives cells shape and form

Links cells together

Microtubules

Hollow tubular fibers

Tubulin protein

Cytoskeleton tracks continued

Microtubules tracks guide chromosomes during mitosis

Motility = flagella (sperm tails)/cilia (tracheal cells)

Histology

Study of structure and function of tissues

Tissue classification

Shape/size

Arrangement (scattering/layering)

How cells connect to each other

Amount of extracellular material present

Extracellular matrix

Substances synthesized and secreted by cells to provide support, communication, and transport

Made of insoluble proteins and proteoglycans

Insoluble proteins examples

Collagen, keratin, myosin, elastin

Adhesive glycoproteins examples

Fibronectin, laminin

Proteoglycans use

Acts as a cushion to withstand compressional force

Cellular components

Joined by specialized cell junctions

Formed by cellular adhesion molecules with 3 types of cell junctions

Cell junction types

Gap

Tight

Desmosome

Gap Junctions

Connexin interlock creating tubes that connect the cytoplasm, allowing direct cell-to-cell communication (allowing pages of ions, discontinuous)

Membrane protein = connexin proteins

Examples = cardiac muscle

Tight junctions

Occluding junctions that are partly fused together by proteins to restrict molecule movement

-Occluding junctions physically link plasma membranes and are continuous

Membrane protein = claudin and occluding

Examples = intestinal mucosa to prevent intestinal contents from leaking into the cellular layer

Anchoring junctions

Cadherins connect across the intracellular space to hold cells together and to the matric using interlocking proteins which act like a zipper, contributing to mechanical strength

Anchoring Junctions - cell-to-cell junction

Junction = desmosome

High tensile strength

Discontinuous

Membrane spanning proteins anchored by plaques = cadherin

Examples - linkage between muscle cells

Anchoring Junctions - cell-to-matrix junction

Junction = hemidesmosome (half a desmosome)

Membrane protein = integrin

Examples - skin, heart

Epithelial tissue roles

Protects internal environment and regulates the exchange of materials

Epithelial tissue location

Cover exposed surfaces

Line internal passageways

Epithelial functional classification

Exchange, transport, ciliated, protective, secretory

Simple

Single layer of cells

Stratified

Multiple layers of cells

Pseudostratified = uneven layering of cells - stratified is usually very neat

Squamous

Flattened cell shape - skin

Cuboidal

Cubic shape - glands

Columnar

Tall - intestinal mucosa

Exchange epithelium

Loosely connected simple squamous cells

Solutes readily pass through cells or pores between cells

Endothelium of capillaries

Transport epithelium

Simple columnar with tight junctions

Apical side faces exterior, basolateral side faces other cells or tissues - different functions than apical side - basement membrane separates from underlying connective tissue

Intestinal mucosa

Ciliated epithelium

Simple columnar

Cilia on the surface beat in rhythm, moving extracellular material

-Intestinal mucosa

Protective epithelium

Stratified and sometimes keratinized

Prevents exchange (moisture loss, etc)

Lines internal cavities

-Skin, scalp, etc

Secretory epithelium

Simple cuboidal

Secretes hormones, enzymes, sweat, milk, mucus

Mucus = protective fluid = glycoproteins

Connective tissue types

Structural = adipose/bone/cartilage

Support = bone/cartilage

Linkages = tendons/ligaments/dermis/blood

Connective tissue

Often overlooked but probs most important

Comprised of cells and extracellular matrix

Cells secrete proteins for the matrix

Fibro

Fiber

Chondro

Cartilage

Adipo

Fat

Osteo

Bone

Hemo

Blood

Blast

Secretes extracellular materials

Cyte

Trapped in extracellular material - usually isolated from adjacent cells

Clast

Cell that destroys extracellular materials

Connective tissue extracellular matrix

Fibrous, insoluble proteins - provides strength and forms - collagen, fibrinogen, elastin

Ground substance - other molecules in the protein matrix, like water, crystalline deposits (bone), glycosaminoglycans (GAGs)

Hyaluronic acid

Carbohydrates - very viscous fluid, absorbs water and a lubricant

Part of the ground substance in extracellular matrix in connective tissue

Chondroitin sulfates

Carbohydrates - more solid than Hyaluronic acid - combines with proteins

Part of the ground substance in extracellular matrix in connective tissue

Loose Cartilage (Loose CT)

Dermis, slightly different but similar in tendons/ligaments

Cells = fibroblasts

Insoluble protein = collagen, elastin

Ground substance= water and glycosaminoglycans (GAGs)

Cartilage (Dense CT)

Found largely at skeletal joints

Cells = chondroblasts

Insoluble protein = collagen - secreted by the chondroblasts

Ground substance = glycosaminoglycans (GAGs)

Large amount of hyaluronic acid and chondroitin sulfate

Dense CT changes

 As GAGs are secreted, chrondroblasts become isolated

◦Now called chondrocytes

◦Receive nutrients via diffusion - (New functions!)

Bone

Cells = osteoblasts

Insoluble protein = collagen - forms bone outline (osteoid) and then filled with ground substance

Ground substance = Ca3+

Bone growth

As it grows, osteoblasts become separated and turn into osteocytes

Lies in small cavities called lacunae

These cells have long cellular extensions called filopodia

Form Haversian systems to transfer nutrients in a bucket brigade

Haversian systems

◦Concentric rings of osteocytes and adjacent ground substance around a central channel with blood vessels

Blood

Cells = hemocytes

Insoluble protein = fibrinogen (precursor protein for blood clot fibers)

Ground substance = water

Blood cell types

Red blood cells - RBC - erythrocytes

White blood cells - WBC - leukocytes

Platelets - thrombocytes

Adipose

Immature cells = fibroblasts

Mature cells = adipocytes

Protein = collagen

Ground substance = water and glycosaminoglycan (GAGs)

Any loose connective tissue can become adipose tissueDi

Difference between adipose and bones

Lipid is intracellular, whereas bone’s main component is extracellular

Muscle tissue

Movement, contraction

Skeletal, cardiac, smooth

Nervous tissue

Communication, control

Glial (glue) - offer physical and biochemical (communication) support to neurons

Neurons

Nerve cell - smallest functioning unit in the nervous system

Rely on disequilibrium to trigger chemical release into extracellular fluid

Nerves

Axons of neurons