Bio 110 Exam 2 Review- Purdue University

What is the most basic unit of life?

Cells

List the characteristics of life

1. Organization/Complexity

2. Responds to the environment (homeostasis)

3. Growth+Metabolism

4. Reproduction/Heredity

5. Evolve

6. Composed of 1 or more cells

What are the basic categories of cells?

Prokaryotes and Eukaryotes

What are the two types of prokaryotes?

Eubacteria and Archaea

List what every prokaryote has

1. Cell Wall

2. Plasma Membrane

3. Cytoplasm

4. Ribosomes

5. Nucleoid

What is the nucleiod?

Where DNA is in a prokaryotic cell

List what makes prokaryotes different from eukaryotes

1. Prokaryotes have no nucleus, DNA is in an area of the cell called the nucleiod

2. Prokaryotes have no internal membrane system

3. All prokaryotes have a cell wall

Cell wall definition

Protective outer barrier of peptidoglycans

List what makes prokaryotes similar to eukaryotes

1. Both use DNA as their genetic material

2. Both have an outer plasma membrane

3. Both have cytoplasm

4. Both have ribosomes

Define cytoplasm

Semi-solid substance containing the cell's internal components

What do ribosomes do

Synthesize proteins

Define pili

Attach to other prokaryotes with the same component to exchange genetic material

Define flagella

Used to whip and move around

Distinct feature of eukaryotes

Internal compartmentalization

List the nucleus's functions

1. Stores genetic information

2. Where ribosomes are assembled

3. Where RNA is produced (transcription)

Define nuclear envelope

A double lipid bilayer membrane that defines the nucleus

What is the outer lipid bilayer connected to?

Smooth and Rough Endoplasmic Reticulum

Define Nuclear Pores

Passages through the nuclear envelope that regulate nuclear transport

Define chromatin

Chromosomal DNA that is bound to DNA binding proteins

Where is chromatin found?

Inside the nucleus

Define the nucleolus

An area inside the nucleus where ribosomes are assembled

Is the nucleolus an organelle?

No

List the endomembrane system components

1. Smooth and Rough Endoplasmic Reticulum

2. Golgi Apparatus

3. Vesicles

What makes the rough ER different from the smooth ER?

Rough ER has ribosomes

What is the structure of the endoplasmic reticulum

It's a network of interconnected tubules

What is the space inside the tubule called

The lumen

What are the functions of the smooth ER

1. Lipid synthesis

2. Chloesterol synthesis

3. Fatty acid synthesis

4. Some carbohydrate synthesis

What are the functions of the rough ER

Protein synthesis

List the options where proteins the rough ER makes will end up

1. Bound for export from the cell

2. Going to be associated with the outer plasma membrane

3. Going to be used in the endomembrane system

What is the Golgi Apparatus's structure

A series of flattened tubes; walls of tubes are a lipid bilayer

What are the Golgi Apparatus's functions?

1. Could modify proteins/molecules

2. Molecules are sorted by destination

3. Molecules are released in vesicles

What does the Golgi's cis face do?

Receives transport vesicles from the ER

What does the Golgi's trans face do?

Where transport vesicles exit from the Golgi

Define exocytosis

The process why which bacteria is exported out of the cell

Define endocytosis

Where material is taken into a cell

How does endocytosis work

The plasma membrane surrounds material from outside the cell and traps it in an endocytic vesicle. This endocytic vesicle then fuses with a digestive vesicle (aka a lysosome)

Define lysosomes

Membrane bound vesicles with low internal pH (4.5-5) that contain digestive enzymes

What are lysosomes' functions

To digest;

1. Material from outside the cell

2. Material from inside the cell (worn-out organelles)

What are new lysosomes called?

Primary lysosomes

How are secondary lysosomes formed?

A primary lysosome fusing with an endocytic vesicle or a cellular organelle

Why is Tuberculosis Bacterium dangerous specifically to do with lysosomes?

Stops primary lysosome from bonding with the endocytic vesicle

What is mitochondria's structure?

A double lipid bilayer membrane

Describe the outer membrane of the mitochondria

Covers the entire organelle

Describe the inner membrane of the mitochondria

Is intensively infolded

What are the folds of the inner membrane of the mitochondria called?

Cristae

What is the 'liquid center' of the mitochondria called?

The matrix

What is the function of the mitochondria?

Energy metabolism (ATP production)

What is the endosymbiotic theory?

Mitochondria and chloroplasts were once free-living prokaryotic cells which developed an endosymbiotic relationship with modern day eukaryotic cells

What are the three major lines of evidence for the endosymbiotic theory?

1. Dividing through binary fission

2. Have their own chromosomal DNA

3. Have their own ribosomes

What is the structure of chloroplasts?

A double lipid bilayer membrane

Define thylakoid

A single membrane cell within chloroplasts' double lipid bilayer

Define granum

A stack of thylakoids

Define stroma

The liquid substance surrounding the inside of the cell for chloroplasts

What is the function of the chloroplast?

They are the site of photosynthesis in plant cells

What two organelles does the endosymbiotic theory apply to?

The mitochondria and the chloroplasts

What is the structure of the cytoskeleton?

A network of multiple types of proteins INSIDE of cells

What are the functions of the cytoskeleton?

1. Provides structural support

2. Has a role in transport within cells

3. Helps mobile cells move

What is the structure of the extracellular matrix?

A network of multiple types of proteins OUTSIDE of cells

What are the functions of the extracellular matrix?

1. Provides structural support outside of cells

2. 'glues' cells into higher order structures (organs)

3. Has a role in cell-cell communications

Define the plasma membrane

A selective barrier that defines the inside and outside of a cell

What is the function of the plasma membrane?

Regulates transport into/out of cells

What are the two things cells can adjust about the plasma membrane?

1. The chemistry of it

2. The molecules associated with it

Describe why Dr. Gorter's experiments worked specifically for red blood cells.

Once red blood cells mature, they do not have internal membrane systems, so there were no other phospholipids to interfere with the discovery of the plasma membrane's lipid bilayer.

What did Dr. Gorter's experiments determine?

That the plasma membrane is a lipid bilayer

What does the fluid mosaic model say?

That plasma membranes are fluid structures

Describe what happened in the cell fusion experiment

The early stages showed no mixing of the two separate membrane proteins, but later stages showed the mixing, proving the plasma membrane is fluid

Describe the photo-bleaching experiment

The membrane proteins were lit with fluorescent dye, then the cell was hit with a laser beam that bleached the area of the cell's surface, and eventually the fluorescent molecules diffused back into the bleach area, proving fluidity.

What happens if the membrane is too fluid?

The membrane will no serve as a barrier and will fall apart

What happens to transmembrane proteins if the membrane is too solid?

Transmembrane proteins will not be able to flex (change their shape) and carry out their functions

What are the two ways cells can change the fatty acid chains of phospholipids to regulate fluidity?

1. Generate phopholipids with more/fewer fatty acid chains

2. Generate phospholipids with longer/shorter fatty acid chains

How do more unsaturated fatty acids pack?

They pack less tightly (looser)

How do more saturated fatty acids pack?

They pack more tightly

How do shorter fatty acid chains pack?

They pack less tightly (looser)

How do longer fatty acid chains pack?

The pack more tightly

What will the cell do if the membrane is too solid?

Cells will increase the concentration of phospholipids with short fatty acid chains and unsaturated fatty acids

What will the cell do if the membrane is too fluid?

Cells will increase the concentration of phospholipids with long fatty acid chains and saturated fatty acids

What happens to the plasma membrane of cells that are exposed to higher temperatures?

The plasma membrane will become more fluid

Define cholesterol

An amphipathic lipid with a hydrophilic head and a hydrophobic ring and hydrocarbon tail

Where is cholesterol present?

In the plasma membrane of eukaryotic cells

What is cholesterol's function?

Helps regulate fluidity of plasma membranes

Which situation is cholesterol useful in?

Both when the membrane is too solid and too fluid

How does cholesterol help when the membrane is too solid?

The steroid ring of cholesterol interacts with and partially immobilizes the phospholipid fatty acid chains, giving the cells time to adjust

How does cholesterol help when the membrane is too fluid?

It prevents the phospholipid fatty acid chains from packing together too tightly

What is the major barrier for molecules crossing a plasma membrane?

The hydrophobic interior

What is the plasma membrane permeable to?

Nonpolar molecules

What is the plasma membrane less permeable to?

Small polar molecules

What is the plasma membrane not permeable to?

Large polar molecules or ions

What are the types of membrane transport?

Passive transport (diffusion) and active transport (anti-diffusion)

Define passive transport

The movement of molecules across the membrane from high concentration to low concentration

Does passive transport require energy input?

No, no energy input is required

Define active transport

The movement of molecules across the membrane from low concentration to high concentration

Does active transport require energy input?

Yes, energy input is required

What are the two types of passive transport?

1. Simple diffusion

2. Facilitated diffusion

What are the two steps required for simple diffusion?

1. The plasma membrane is permeable to a particular molecule

2. There is a difference in concentration of that molecule across the membrane

Are transport proteins required for simple diffusion?

No, no transport proteins are required

Define facilitated diffusion

Diffusion of molecules that can't cross the membrane on their own

Does facilitated diffusion require transport proteins?

Yes, transport proteins are required

What does transport proteins being selective mean?

Means that they only transport certain molecules

What are the two types of transport proteins?

1. Channel proteins

2. Carrier proteins

Which transport protein does not bind to the molecules they transport?

Channel proteins