BIO1100 Dr. Morris Troy University Exam 2 - Module 3, Cells

Why are cells so small?

• efficient exchange of substances w/the environment;

• ideal cell size has large SA:V ratio

Prokaryotic Cells

• no nucleus

• no membrane-bound bodies

Prokaryotic vs. Eukaryotic cell size?

• Prokaryotic = small — 1-10 micrometers

• Eukaryotic = larger — 10-100 micrometers

How do scientists identify types of prokaryotic cells?

Their SHAPE

Types of prokaryotic cells:

• bacillus

• coccus

• spirillum

• vibrio

Bacillus

= rod-shaped

• Commercial use — dairy products for digestion

• Environment — decomposition agents

Coccus

= spherical

• Commerical use — source of antibiotics

• Environment — agents of disease

Spirillum

= twisted rod / “s”-shape

• Lyme disease-causing bacteria

  • Can be chronic, affects multiple organ systems

Vibrio

= shape of comma

• Flesh-eating bacteria

  • On beach in AL, in seafood during months without “r”

Eukaryotic cells

• Have a nucleus

• Have membrane-bound bodies

Plant vs. Animal cells:

Plant Cells:	Animal Cells:
Nucleus off to side Cell Membrane AND  Cell Wall Large Central Vacuole Chloroplast	Nucleus more central Cell Membrane Lysosome

Protoplasm

• in all eukaryotic cells

• contains cell contents (nucleus & cytoplasm)

Nucleus

• control center of cell

• contains genetic material (DNA)

Types of genetic material in nucleus:

• Chromatin

  • in non-dividing cells

  • sandpaper-like (little dots)

• Chromosomes

  • in dividing cells

  • thread-like

Nucleolis

• = center of nucleus

• cells have 1-4 nucleoli

• Make ribosomes

Ribosomes

make proteins to result in characteristics

Cytoplasm

• area of cell that isn’t nucleus

• contains cytosol and membrane-bound bodies

Cytosol

= liquid surrounding all membrane-bound bodies

2 types of Membrane-bound bodies

• Endomembrane system

• Organelles

Parts of the Endomembrane system:

• RER

• SER

• Golgi Body

• Lysosome

• LCV

Organelles:

• Mitochondrion

• Chloroplast

RER

• aka Rough Endoplasmic Reticulum

• Makes proteins to result in characteristics

• covered in Ribosomes

• More found in muscles

SER

• aka Smooth Endoplasmic Reticulim

• Makes lipids to detoxify cell

• NOT covered in ribosomes

• More found in liver

Golgi Body/Apparatus

• makes carbs for cell

LCV

• aka Large Central Vacuole

• only in PLANT cells

• Big water bag in mature plant cell

4 functions of the LCV:

1. Structure (balance of 2 pressures keeps plants upright)

2. Storage

3. Crystals

4. Pigments

Turgor pressure

water pushes out on flexible LCV —> pushes on flexible Cell Membrane —> pushes on rigid Cell Wall

Wall pressure

rigid Cell Wall pushes back

What happens when plants don’t get enough water?

lack of pressure balance —> wilting

What does the LCV store?

Water, Vitamin C, energy

Crystals in LCV

• made of Calcium Oxalate

• 2 shapes

• Defense against herbivores;

  • numbs muscles in oral cavity —> loss of speech

  • discomfort —> feel like walking pincushion

What pigments the LCV?

• bright colored

• Anthocyanins (blue, purple, crimson, & black)

In what are anthocyanins found?

• Flowers (attracts insects for pollination)

• Fruit (attracts animals for dispersal)

• Leaves in fall (temp drops, day gets longer, gets dryer —> denatures chloroplasts, LCV pigments show through)

Mitochondrion (in what & what they do)

• in every eukaryotic cell

• extra in muscles

• Mitochondria = “powerhouse” of cell — transforms food —> energy thru Cellular Respiration

Chloroplast (in what & what they do)

• only in plants, algae, seaweeds, & a FEW bacteria

• do Photosynthesis

3 ways photosynthesis benfits the world:

“FOG”;

1. kickstarts the Food chain

2. puts Oxygen into atmosphere

3. slows down Global climate change by taking in CO₂

What is the Fluid-Mosaic Model?

Models cell membrane structure — “Fluid” = almost liquid in texture, “Mosaic” = different components working together

Parts of Cell-Membrane / Fluid-Mosaic Model

• Phospholipid bilayer

• Protein

• Carbohydrate

• Cholesterol

• Extracellular Matrix (ECM)

Phospholipid Bilayer (what it is & what it does in cell membrane)

• “Regulator” — controls what goes in/out of cell

• made of 2 layers of phospholipids, base of membrane

  • heads = glycerol + phosphate, more hydroPHILIC

  • tails = 2 fatty acids, very hydroPHOBIC

What passes easily through the Phospholipid Bilayer?

Characteristics:

• small

• hydroPHOBIC (just like fatty acid tail portion)

ex. O₂ ; CO₂

Protein (what it is & what it does in cell membrane)

• “Ships” in a “sea” of lipids — transport “cargo” (esp. hydrophilic substances that have a harder time getting through hydrophobic fatty acids) through p.b.

• Tube-like blobs running through membrane, can move left ←→ right to allow things to pass through anywhere

Carbohydrates (what it is & what it does in cell membrane)

• “Gatekeepers” — work w/immune system to allow self-molecules and reject non-self-molecules from crossing p.b.

  • tissue/organ transplants, doctors must suppress immune system so body doesn’t attack foreign carbohydrates

• Linked glucose (pentagon-shaped sugar) units, hang off edge of membrane

Cholesterol (what it is & what it does in cell membrane)

• maintains proper texture of membrane — more rigid / fluid when needed

• go along with fatty acid tails

Extracellular Matrix (what it is & what it does in cell membrane)

• aka ECM

• Support, Protection, & Controls activity inside cell

  • Different consistencies in different connective tissues; in BONE tissue = SOLID, in BLOOD = LIQUID (plasma)

  • Collagen found here

• Fibrous-like structures on INNER edge

2 kinds of transport processes

Passive & Active

Passive transport (ATP/cost, charge, hydro-, size, concentration gradient?)

• DON’T require ATP from cell, NO cost

• happen SPONTANEOUSLY

• Usually UNcharged, hydroPHOBIC, SMALL molecules moving WITH concentration gradient

4 types of Passive transport:

1. Bulk Flow

2. Diffusion

3. Osmosis

4. Facilitated Diffusion

Bulk Flow

= COORDINATED movement of LIQUID molecules ACROSS membrane from region of HIGH concentration —> LOW concentration; aided by GRAVITY
ex. waterfalls, sap flowing down trees

Diffusion

= RANDOM movement of ANY KIND of molecules from a region of HIGH concentration —> LOW concentration ACROSS or NOT across a membrane until DYNAMIC EQUILIBRIUM is reached

Dynamic Equilibrium

= equal rates of movement back & forth

Osmosis

= DIFFUSION of WATER molecules ACROSS SELECTIVELY PERMEABLE membrane

• ONLY movement of water

• MUST be membrane involved

Essential for Osmoregulation

Osmoregulation

= maintenance of a proper water balance

very important for proteins

Solute

Substance being dissolved; solid (ex. salt)

Solvent

Substance the solvent is being dissolved into; liquid (ex. water)

**remember by “dissolVENT”

Solution

Mixture of solvent & solute

Hypertonic

solute (salt) > solvent (water)

in solution on one side compared to other side of selectively permeable membrane

Isotonic

solute (salt) = solvent (water)

in solution on one side compared to other side of selectively permeable membrane

Hypotonic

solute (salt) < solvent (water)

in solution on one side compared to other side of selectively permeable membrane

** remember because rhymes w/H₂O —> more water / solvent

What cells prefer an isotonic environment?

Land animal, human

What cells prefer a hypotonic environment?

Aquatic animal, plant

2 special adaptations of fish:

1. Gills — release CO₂ and excess H₂O

2. Efficient bladders — pee filters out excess H₂O

What cells prefer a hypertonic environment?

Some bacteria

ex. bacteria in Great Salt Lake, Utah

Facilitated Diffusion

RANDOM movement of ANY KIND of molecules from region of HIGH concentration —> LOW concentration ACROSS membrane; aided by PROTEIN (boosts reaction) in cell membrane

ex. movement of glucose from small intestine —> bloodstream

When do proteins help most with Facilitated Diffusion?

****SMALL difference in concentrations, happens SLOWer (not as urgent?) —> needs protein’s help (ex. 60% —> 40%)

vs.

BIG difference in concentrations, happens FASTer (ex. 90% —> 10%)

Active transport (ATP/cost, charge, hydro-, size, concentration gradient?)

• DO require ATP from cell, MORE costly

• usually CHARGED, hydroPHILIC, BIG molecules moving AGAINST concentration gradient

2 types of active transport:

1. Endocytosis

2. Exocytosis

Endocytosis

= movement of BIG molecules AGAINST concentration gradient INTO cell

2 types;

2 kinds of Endocytosis:

• PHAGOcytosis

• PINOcytosis

Phagocytosis

= large SOLIDS taken in; “cell is EATING”

ex. white blood cells eating viruses, foreign substances

Pinocytosis

= large LIQUIDS taken in; “cell is drinking”

generalized / widespread in plants & animals

**remember because “pino” sounds like “pinot noir” wine

Exocytosis

= movement of BIG molecules AGAINST concentration gradient OUT of cell

ex. hormones

Hormones & exocytosis

HGH (human growth hormone); pituitary gland —> bones, muscles, etc.

Insulin; pancreas —> bloodstream

All living things must ______.

Take in and use energy

Thermodynamics

= study of energy transformation

2 laws of thermodynamics:

1. Law of Conservation of Energy

2. Entropy

Law of Conservation of Energy

• “Energy is neither created nor destroyed in an energy transformation”

• total Reactant energy = total Product energy

Entropy

• “There is an increase in the amount of disorder in a system in an energy transformation”

• Living things try to fight it

Catabolic

= BREAKING DOWN larger molecules to smaller molecules to GENERATE energy

**remember because “cat-astrophe” = something breaking down or being destroyed

Anabolic

= USING energy to PUT TOGETHER small molecules into bigger molecules

Exogenic

= MORE p.e. in REACTANTS, LESS p.e. in PRODUCTS, & RELEASE of energy to do work

**ex-ITing is leaving

Endogenic

= LESS p.e. in REACTANTS, MORE p.e. in PRODUCTS, & NO release of energy to do work

**en-TERING is NOT releasing

Cellular Respiration (goal, what does it, enzymes?, -bolic / -genic, where it happens, equation)

• Goal = getting ATP to do work

• done by ALL living things

• each step in chain of reactions has special enzyme

• happens in Mitochondria in eukaryotes (in cytosol/cytoplasm in bacteria)

• Catabolic

• Exogenic

• 2 kinds;

Aerobic Cellular Respiration

= takes place IN presence of oxygen; NORMAL cellular resp.

Anaerobic Cellular Respiration

= takes place WITHOUT oxygen when undergoing strenuous activity you’re not used to (heart can’t pump O₂ fast enough to make sugar to supply muscles); leads to Alcohol / Lactic Acid fermentation

Lactic Acid (made in what, what it causes)

• made in humans, animals, & bacteria that do c.r.

• forms and builds up in muscles —> causes burning cramping

• Goes away when resting —> O₂ levels go back up —> lactic acid converted too another substance that doesn’t cause cramping

Alcohol / Ethanol (made in what, what it is used for)

• produced in plants & fungi that do c.r.

• Process is impportant to fuel, baking & brewing industries

• ex. Yeast = unicellular, can’t survive in the alcohol (toxin) it makes

• ex. plants like Corn = source of ethanol added to gasoline

Photosynthesis (goal, what does it, -bolic / -genic, where it happens, equation)

• Goal = storing up energy to be used later on

• happens in Chloroplasts in eukaryotes (in cytosol/cytoplasm in bacteria)

• Anabolic

• Endogenic