Bio Exam Review

3UW terms + description + more

Characteristics of Life

Nutrition, reproduction, respond to stimuli, growth and development, metabolism, excretion, evolution, made of cells, and homeostasis.

Homeostasis

Maintaining a stable internal environment

Metabolism

All biochemical reactions that occur in an organism

Chemical properties of water

Polar molecule, cohesion (molecules stick together), adhesion, high boiling point due to H-bonds, can become habitats because of H-bonds, universal solvent

Hydrophilic + examples

Any substance that water dissolves.

Examples: glucose in blood, oxygen in blood

Who proposed cell theory?

Schwann and Schleiden in 1838

6 Laws of Cell Theory

1. All living things are made of cells

2. Cells are the fundamental units of structure and function in living organisms

3. All cells come from pre-existing cells

4. Cells contain a blueprint for growth, development, and behaviour (DNA)

5. Energy flow occurs within cells

6. Site of chemical reactions

What are the exceptions to cell theory?

• Where did the first cell come from?

• Algae growing up to 100 mm in size but still only being one cell big

• Aseptate fungi hyphae are long thin string like structures with multiple nuclei

• Striated muscles in humans have multiple nuclei

• Red blood cells do not have a nucleus

• Xylem and Phloem don't have nuclei

What 5 features do all cells share?

1. Cell membrane

2. DNA

3. Enzymes to catalyze chemical reactions

4. Store energy in form of ATP

5. Carry out functions of Life

Why are cells good building blocks?

1. Limited by surface to volume ratio

2. Rate of exchange is affected if cell gets too big

3. Cell may overheat if cell is too small as metabolism is too fast

Properties of unicellular organisms?

1. Face environment on all sides

2. Damage to cell could mean death

3. Good ability to regenerate

4. Lower levels of efficiency

Emergent properties of multicellular organisms?

1. High operational efficiency

2. Different cells perform different functions

3. Only outer cells are specialized to face outside environment

4. In case of injury and death of cells, it can be replaced

Differentiation

Certain groups of cells perform specific functions while other groups perform other functions. It involves the expression of some genes and not others.

Advantage of differentiation

Allows for more cell efficiency

STEM cell definition

undifferentiated cells which are found in multicellular organisms and have the ability to divide and differentiate along different pathways

Types of STEM cells and definitions?

1. Totipotent - eight cells can become any cell or organism

2. Pluripotent - can become any type of body cell from the blastocysts

3. Multipotent - umbilical cord stem cells, can become any closely related cell (used in spinal injuries and bone fractures)

4. Unipotent - cells that can become cells like themselves found from adult tissues (liver cells become liver cells, used in transplants)

Uses of STEM cells

1. Leukemia - bone marrow transplants, allowing tissues to produce healthy blood

2. Type 1 Diabetes - embryonic stem cells that tun into islet cells, producing insulin

3. Stargardt's Disease

Ethical Arguments

1. When STEM cells are harvested, the embryo dies

2. Cells harvested from umbilical cord have limited capacity to differentiate

3. Adult STEM cells are difficult to obtain and limited potential

List 5 characteristics of Light Microscopes

1. natural colour

2. large field of view

3. cheap and easy preparation

4. view live, moving, and dead

5. view whole

6. mag up to 2000x

List 5 characteristics of Scanning Electron Microscopes

1. View in black and white

2. limited FOV

3. must be places in a vavuum

4. view surface only of organism

5. mag up to 500,000x

List 5 characteristics of Transmission Electron Microscopes

1. view in black and white

2. limited FOV

3. difficult and expensive preparation

4. view dead or frozen objects

5. magup to 1 million

6. view a thin section of sample

Which is type of microscope is this? (E.coli under microscope)

Transmission Electron Microscope

Which is type of microscope is this? (E.coli under microscope)

Scanning Electron Microscope

Which is type of microscope is this? (E.coli under microscope)

Light Microscope

Characteristics of prokaryotes + example(s)

1. unicellular

2. small

3. simple structure

4. found everywhere on earth

ex: bacteria and archaea

DNA in prokaryotes

• lack nucelus

• found in a circle (nucleoid region)

• some DNA found in forms of plasmids

What are plasmids?

They are small pieces of DNA that replicate independently of the DNA nucleoid. They often contain the genes for antibiotic resistance.

Cell Wall characteristics in prokaryotes

1. some made of peptidoglycan (sugar and protein)

2. Many have glycocalyx - sticky layer made of sugar and amino acids which form protective layer around the bacteria

Parts of prokaryote

1. DNA

2. Cell well

3. Plasma membrane - phospholipid bilayer that controls movement in and out the cell

4. Cytoplasm

5. Ribosomes - free floating in cytoplasm, site of protein production

6. Fimbriae - short protein tubules for attachment

7. Plli - longer protein tubules used for attachment and transfer of DNA

8. Some have flagella - allow bacteria to move

How do prokaryotes reproduce?

1. binary fission - the DNA replicates and the cell divides forming two cells with identical DNA (mitosis)

2. transduction - virus

3. conjugation - transferred

4. transformation - cytoplasm

Characteristics of eukaryotes

1. larger than prokaryotes

2. contain nucleus and nucleolus

3. plasma membrane and phospholipid bilayer

4. multiple strands of DNA

5. cytoplasm

6. cytoskeleton

7. contains many membrane bound organelles - mitochondria, smooth and rough er, lysosomes, vacuoles, chloroplasts

What is compartmentalization?

The organization of eukaryotic cells into various organelles that perform specific functions

What are the advantages of compartmentalization?

• allows for unique processes to occur without interference

• chemicals can be more concentrated, like enzymes

• cells are much more efficient

• larger area for process to occur

What organelle is this?

Golgi apparatus

What organelle is this?

Chloroplast

What organelle is this?

Endoplasmic reticulum

What organelle is this?

Mitochondria

What are phospholipid molecules made of?

1. Hydrophilic phosphate head with glycerol (water loving)

2. Hydrophobic lipid tails (water hating), tails are attracted to one another

3. Amphipathic - parts of same molecule are attracted to water and other parts are not

Characteristics of plasma membranes

1. semi fluid

2. moves laterally (floating)

3. can flip-flop

4. semi-permeable

5. viscosity of vegetable oil at room temp

6. contains proteins and cholesterol

7. water, oxyge, and carbon dioxide diffuse across membrane

8. impermeable to most ions

9. impermeable to most water soluble molecules

What are the types of membrane proteins?

1. Integral proteins

2. Peripheral proteins

3. Cholesterol

4. Glycolipids

5. Lipid-anchored protei

Characteristics of integral proteins

• embedded in bilayer

• cannot be released

• hydrophobic on part of the surface

• many are trans-membrane (transmembrane proteins)

• some are partially embedded

Types of integral proteins

1. Channel proteins - for passive transport. This allows hydrophilic substances through by facilitated diffusion

2. Protein pumps - active transport. These proteins us ATP to move particles against the concentration gradients

3. Carrier proteins - They change shape to move ions with the concentration gradient

4. Receptor proteins - Bind extracellular substances like enzymes or hormones that trigger cell activity to change. More than one protein can work together to make a metabolic pathway.

5. Adhesion proteins - help cells of the same type to stick together and form tissues

Voltage-gated ion channel

passive vs active transport

Characteristics of peripheral proteins

1. proteins that are attached to the inner or outer surface of membrane

2. they can be attached to proteins or lipids

3. they are hydrophilic

Types of peripheral proteins

1. Glycoproteins - act as communication and identification tags.

2. Support proteins - help hold the cytoskeleton in place and provide structural support for the cell

3. Adhesion proteins - help cells of same type to stick together and form tissues

Six major functions of membrane proteins

1. Transport channels

2. Receptors (hormones)

3. Anchorage

4. Enzymetic activity

5. Signal induction

6. Cell recognition

7. Inter cellular connection

8. attachment to cytoskeleton and extracellular matric

Characteristics of cholesterol

• steroid

• mainly hydrophobic

• amounts vary cell to cell

Function of cholesterol

• increase fluidity at low temp

• reduces fluidity at high temps

• holds phospholipids together

• prevents crystallization

• reduces permeability to Na and H

• Assists in formation of vesicles during endocytosis

What are glycolipids and what do they do

• molecules which are carbohydrates linked to lipids

• help the immune system to distinguish between self and non self

• glycoproteins form the glycocalyx