KIN223 - CH4

Taken from block 2 learning objectives

How does light microscopy work?

• Passes light through the specimen

• provides a 2D image

How does transmission electron microscopy work?

• Directs electrons THROUGH thin cut SECTIONS

• 2D images

How does scanning electron microscopy work?

• Directs electron beam ACROSS the SURFACE

• 3D image

What is the size range of human cells?

• Erythrocytes are 7-8 um

• Oocytes are around 120 um

What are the shapes human cells take?

• cube (

• column

• cylindrical

• disc

• irregular

THREE MAIN structures of a cell

• Plasma membrane

• Cytoplasm

• Nucleus

Membrane bound organelles

GLEPM

• Golgi apparatus

• Lysosomes

• Endoplasmic reticulum (S/R)

• Peroxisomes

• Mitochondria

Non-membrane bound organelles

PRCC

• Proteasomes

• Ribosomes

• Centrosome

• Cytoskeleton

Cell’s general functions

SWaNDive

• Shape and integrity maintenance

• Waste disposal

• Nutrient obtainment

• Division of cell

Lipid components of membrane

• Phospholipids

• Cholesterol

• Glycolipds

Phospholipid function in membrane

• Uses hydrophobic head for internal environment, uses hydrophilic head outside

• creates a bilayer that keeps things in and out

Cholesterol function in membrane

• 4 ring lipid molecule

• Strengthens the membrane and aids with temperature change

Glycolipid function in membrane

• lipid + carbohydrate group formed on outside of phospholipid region

• maintains stability in the membrane

What are the 2 membrane proteins

1. INTEGRAL protein - extends across the bilater

2. PERIPHERAL protein - attached to outside or inside of bilayer

Explain the six major roles played by membrane proteins.

TEACIC “tea kick”

• TRANSPORT - regulate movement across membrane

• ENZYMES - attached to inter/external surfaces for reaction catalyzing

• ANCHORING - securing membrane to the cytoskeleton

• CELL SURFACE RECEPTORS - ligand binding

• IDENITY MARKING - communication with other cells

• CELL ADHESION - cell to cell attachment

Diffusion

• Passive process involving net movement down a concentration gradient

• Continues until equilibrium

Simple diffusion

• Molecular movement is unassisted between phospholipid molecules with no membrane

• Involves small and nonpolar molecules

Facilitated diffusion

• Molecular movement uses channel or carrier mediated proteins to cross membranes

• involves polar solutes

Osmosis

The diffusion of WATER

Osmotic pressure

Pressure created by water crossing a membrane

How do osmosis and tonicity relate?

• Tonicity is directly affected by osmosis, becoming hypotonic, isotonic, or hypertonic depending on the amount of water in or out of the membrane

Primary active transport

• Utilizes ATP to push something across the membrane

• involves the Na/K pumps, 3 out and 2 in

Secondary active transport

• Catches a ride with another molecule

• Symport or antiport, going in the same or opposite direction respectively

Exocytosis

• Uses vesicles to move something out of the cell, EXO

• Used for macromolecules that are too large for the membrane

• requires ATP

Endocytosis

• Uses vesicles to move something into the cell, ENDO

• Used for digestion

  • Phagocytosis, pinocytosis, receptor mediated cytosis

Phagocytosis

• cellular eating, packman style

Pinocytosis

• Cellular drinking

• internalized droplets of interstitial fluid contianing solutes

• utilizes smaller vesicles

Receptor mediated endocytosis

• uses receptors to bind molecules and brings them into the cell, gatekeeping

What is RMP?

• The electrochemical gradient made by the membrane, used to for muscle and nerve function

What are the cellular conditions that are needed for maintaining RMP

• needs an unequal distribution of ions across the membrane

• relative amounts of positive and negative charges

• potassium in cytoplasm, Na in interstitial fluid

• Na/K pump

What does K+ and Na+ do for an RMP

• Potassium creates a steep gradient

• sodium diffuses into the cell via leak channels to go down the concentration gradient

How do cells communicate through direct contact

Communication is done via GAP JUNCTIONS

What are the 3 general mechanisms of response to ligands binding with a receptor

• Channel linked

• Enzymatic

• G Protein coupled

Channel linked

• permits ion passage in or out of the cell in response to neurotransmitters

• initiates RMP changes in muscle/nerve cells

Enzymatic

• 2 part process, anzyme enters cell, second substance (gatekeeper) opens cell

G protein coupled

• a chemical messenger attaches and changes the inside

Golgi apparatus

• The packaging and modification of proteins

• made of cisternae, a continuous structure

  • the CIS face is close to the ER, the TRANS face is away from the ER

Lysosomes

• Digests the contents of vesicles

• Small, membrane like sacs

Endoplasmic reticulum

• ROUGH ER

  • synthesizes and modifies proteins, forms vesicles to ship to GA, creates peroxisomes

• SMOOTH ER

  • lipid synthesis, carb metabolism, detox.

Peroxisome

• Membrane enclosed sacs

• detoxifies and breaks down molecules

Mitochondria

• Powerhouse of the cell

• creates ATP, cellular respiration

Proteasomes

• Breaks down damaged proteins with ATP

• quality control

Ribsomes

• Bound ribosomes help the ER make proteins

• Free ribosomes float in the cytosol and just help make protein

Centrosomes

• Separates chromosomes in cell division

• Centriole pair

Cytoskeleton

• Provides structure to the cell

Cilia

hair-like projections that move things along the cell

Flagella

Larger and wider than cilia, propels the cell along

Microvili

extensions of the plasma membrane that increases the surface area

Tight junctions

Keeps things together similar to a nail, made of rows proteins linked to other cells

Desmosomes

Binds neighboring cells, made of proteins

Gap junctions

Direct passageway for substances to travel between cells

Nuclear envelope

• phospholipid bilayer that separates the nucleus from the rest of the cell

Nucleolus

Creates ribosome parts, not present in all cells, made of protein and RNA

DNA

• blue print for proteins

• five carbon sugar, phosphate, ACGT

• bound by phosphodiester bond

Describe the relationship of DNA, chromatin, and genes

• DNA is chromatin when not dividing, become chromosomes in division

What are the structures needed for transcription?

• Nucleus

• RNA polymerase

• DNA

3 Steps of transcription

1. INITIATION

   • DNA unwound by enzymes, RNA polymerase attaches to promoter region

2. ELONGATION

   • free ribonucleotides are base paired with exposed bases on the DNA strand

3. TERMINATION

   • RNA polymerase reaches terminal region of gene, then the newly formed RNA strand is released

   • DNA rewinds

List the required structures for translation.

• ribosomal subunits

• RNA

• mRNA

• tRNA

What are the three functional forms of RNA

• rRNA

• mRNA

• tRNA

Describe the three steps of translation.

1. INITIATION

   • Complex formed between ribosomal subunit

   • base pairing and methionine binds to tRNA

2. ELONGATION

   • tRNA brings charged amino acids, anticodons pair with codons

   • peptide bonds added

3. TERMINATION

   • pairs are released and the units separate

Explain why DNA is considered the cell’s control center.

It is responsible for protein blue prints

Chromatin vs Chromosome

• Chromatin is visible when the cell is NOT dividing, a finely filamented mass

• During DIVISION, they tighten and become chromosomes

What are the phases of the cell

G1, S, G2

What occurs in G1

• Cell and volume growth

What happens in S

• Cell copies its DNA to produce 2 sister chromatids

What happens in G2

• Further cell growth and cellular content organization

What are the events of the mitotic phase?

PMAT

• Prophase

• Metaphase

• Anaphase

• Telophase

Prophase

• chromosomes condense, centrosomes move to opposite sides of nucleus

• nuclear envelope breaks down

• mitotic spindle forms

Metaphase

• chromosomes move together and align in the middle of the cell

Anaphase

• Chromosome pairs are separated into 2 independent chromosomes

Telophase

• chromosomes arrive at opposite poles

Define apoptosis and describe the actions that occur in a cell during apoptosis.

• Apoptosis is programmed cell death

• Cell shrinks as cytoskeleton collapses

• nuclear envelope disassembles and DNA breaks into fragments