Meyers A&P October 23, 2015

UNIT 3

Cells & TissuesChapter 3 & 4

I. Anatomy of a Cell (3 regions) 1. Nucleus:

-control center-houses genetic material

*3 distinct regions of the nucleus:-nuclear membrane - controls what enters & leaves nucleus-chromatin - genetic material-nucleolus - synthesis of ribosomes

2. Plasma Membrane: controls what enters & leaves the cellStructure:> 2 lipid layers (phospholipids) & cholesterol

- hydrophobic & hydrophyllic ends

> proteins (receptors, channels, carriers, enzymes, anchors, identifiers)

- create pores in which material can pass through freely- carrier/transport proteins (binding sites)- glycoproteins - determine blood type

> microvilli - help increase surface area- found on cells that function in absorption

3. Cytoplasm: area between the nucleus and plasma membrane where most cellular activities happen.

Meyers A&P October 23, 2015

Meyers A&P October 23, 2015

II. Cellular Junctions • Connections between adjacent cells...

1. Tight Junctions-Anatomy:

» plasma membrane fused together like a "zipper"

Function: » leak proof, prevents substances from passing

through extra cellular space» found in small intestine - keep enzymes from

"seeping" into our bloodstream

Meyers A&P October 23, 2015

II. Cellular Junctions cont. 2. Desmosomes-

Anatomy:» adhesion junctions (anchoring) - connected

together by protein filaments Function:

» prevent cells from being pulled apart when subjected to stress

» holds skin together

II. Cellular Junctions cont. 3. Gap Junctions-

Anatomy:» membranes held together with hollow protein

filamentsFunction:

» communication between cells» nutrients & ions pass directly from cell to

cell» found in Cardiac muscle tissue

Meyers A&P October 23, 2015

III. Cytoplasm

3 major elements of the cytoplasm:1. cytosol: liquid portion suspends other elements

2. inclusions: chemical substances found in cells- stored nutrients- pigments in skin

3. organelles: metabolic machinery of the cell

Cell Organelles:

A. Ribosomes - protein synthesis

B. Endoplasmic Reticulum - network of channelsSER - lipid metabolism

RER - membrane factory - transport proteins made from ribosomes

C. Golgi Apparatus - modify & package proteins

D. Lysosomes - breakdown materials (digestive enzymes)

E. Peroxisomes - detoxify

F. Mitochondria - powerhouse (produces ATP)

G. Cytoskeleton - cell shape, supports other organelles, intracellular support transport

H. Centrioles - cell division (mitotic spindle)

I. Cilia & Flagella - movement

-compare to your organelle notecards

Meyers A&P October 23, 2015

IV. Cell Transport Basics • Solution - homogenous mixture of 2 or more components

-solute vs solvent

• Intracellular fluid - cytoplasm & nucleoplasm

• Interstitial fluid - exterior (thousands of ingredients)-amino acids, vitamins, fatty acids, sugars

→ Solute dissolves into Solvent

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V. Movement of Substances: Passive vs. Active Passive Transport: no cellular energy is required, go with the

concentration gradient

A. Diffusion - process in which molecules move from an area of higher concentration to an area of lower concentration

*speed of diffusion depends on concentration, size, & temperature

> Simple Diffusion:- molecules are small enough to pass directly through pores in membrane- molecules are lipid soluble

> Osmosis: diffusion of water (aquaporins)

> Facilitated Diffusion:- molecule is too large to pass through pores- not lipid soluble- transport protein (specific) needed to bring it across cell

membrane

-O2, CO2, fatty acids, steroids

-glucose, amino acids, ions

Meyers A&P October 23, 2015

- Hypertonic:

- Hypotonic:

- Isotonic:

B. Tonicity:

V. Movement of Substances Cont. Compare [solute] of 2 Solutions

Greater Solute Concentration↳ Lower H2O Concentration

Lower Solute Concentration↳ Higher Water Concentration

Equal Solute Concentrations↳ Equal Water Concentrations

Meyers A&P October 23, 2015

C. Filtration- water & solutes are pushed across the cell membrane by hydrostatic pressure

- moves by pressure gradient not concentration gradient

- ex. takes place in the kidneys

V. Movement of Substances Cont.

Meyers A&P October 23, 2015

Active Transport: go against concentration gradient & requires ATP

A. Solute Pumping-uses protein carriers and ATP to drive or pump molecules against concentration gradient-ex.

V. Movement of Substances Cont.

Na+/K+ pump

V. Movement of Substances Cont. B. Bulk Transport

-exocytosis - moving large particles out of cell

-Golgi complex - creates vesicles that release molecules

-endocytosis - moving large particles into cell-ex. WBCs

Meyers A&P October 23, 2015

VI. Cellular Respiration- Reaction within mitochondria that converts energy from Carbs*, Proteins & Lipids into usable energy for cells (ATP)

- Reaction split into 3 stages to harness energy:- glycolysis: splits sugar- citric acid (krebs) cycle: separates carbons- electron transport chain (ETC): converts energy --> ATP

Meyers A&P October 23, 2015

VII. Protein Synthesis: Transcription & TranslationGene - sequence of nucleotides that determines physical traits

Transcription: DNA to mRNA

1. DNA unwinds & unzips

2. RNA base pairs with DNA sense strand

3. mRNA strand leaves nucleus & begins translation

↳ Proteins*Coding Regions

VII. Protein Synthesis cont.Translation: mRNA to proteins

1. mRNA attaches to ribosome2. ribosome reads codons (start codon)3. aa brought to ribosome by tRNA4. each codon specifies for an aa5. anticodon (tRNA) base pairs w/ codon (mRNA)6. ribosome continues down mRNA, tRNA brings down next aa &

peptide bond forms7. ribosome reads a stop codon & aa sequence is released

-3 base pair SequenceAUG

Meyers A&P October 23, 2015

Meyers A&P October 23, 2015

VIII. Cell Cycle

Interphase:G1 -

S -

G2 -

- 1 cell divides into 2 identical daughter cells- for growth & repair

growth

DNA synthesis (replicates)

final prep (centrioles)

Meyers A&P October 23, 2015

VIII. Cell Cycle cont. Mitosis:

> Prophase - chromosomes (condensed) - nuclear membrane/nucleoli break down

- centrioles migrate

> Metaphase - sister chromatids in middle

> Anaphase - sister chromatids pulled to opposite poles

> Telophase - chromosomes to chromatin - nuclear membrane/nucleoli reappear - spindle breaks down

> Cytokinesis - division of cytoplasm - cleavage furrow

Division of 1 cell into 2 identical daughter Cells

Meyers A&P October 23, 2015

VIII. Cell Cycle cont.

Cell Differentiation:- when a less specialized cell becomes a more specialized cell with a specific function

Cell Death (Apoptosis):-process of programmed cell death