Lect Chapter 3a

Question 1

Explain the cell theory

Answer 1

– A cell is a structural in functional unit of life
– How well a organism is doingDepends on the individual and combined activities of all it cells.
-Cells can only arise from other other cells
-Function of cells are dictated by the shape of the cells and specific sub cellular structure

Question 2

How many different types of human cells aren there and speak of cell diversity

Answer 2

• 200 Types of human cells

- different structures have different functions

Question 3

What are the three basic parts of a human cell

Answer 3

The plasma membrane and the nucleus and cytoplasm

Question 4

What is the plasma membrane

Answer 4

Flexible outer boundary

Question 5

What is the cytoplasm

Answer 5

Intracellular fluid containing organelles

Question 6

What is the nucleus

Answer 6

DNA containing control center

Question 7

Name some extracellular materials

Answer 7

Extracellular fluids
cellular secretions
extracellular matrix

Question 8

Name extracellular fluids found in the body.

Answer 8

Interstitial fluid
Blood plasma
Cerebral spinal fluid

Question 9

What are extracellular matrix

Answer 9

Substance that acts like glue to hold cells together

Question 10

What are main functions of the plasma membrane

Answer 10

• Acts as an active barrier between intercellular and extracellular fluid
• plays a dynamic role in selectivity controlling what enters and leaves the cell
• aka cell membrane

Question 11

Is the structure of the structure of the plasma membrane

Answer 11

• membrane lipids form flexible lipid bilayer
• specialized membrane proteins (fluid mosaic) float through this fluid membrane
• surface sugars form glycocalyx
• cell junctions help hold the soul together

Question 12

What are the different Membrane lipids and what percentage are each?

Answer 12

• Lipid bilayer made up of 75% phospholipids consisting of two parts the phosphate head which is a polar (charged) and hydrophilic segment and a fatty acid tail which is a nonpolar (no charge)hydrophobic
• 5% glycolipids which is a lipid with a sugar group on the outer membrane surface and -20% cholesterol which increases the membrane as stability

Question 13

Explain broadly what membrane proteins do and describe?

Answer 13

-Allow cell communication with Enviornment
– make up about half the mass of the plasma membrane
– most have specialized membrane functions
– some float freely, and some are tethered to intracellular structures

Question 14

What tasks do the membrane proteins perform?

Answer 14

• transport
• receptors for signal transduction
• attachment to the cytoskeleton and extracellular matrix
• enzymatic activity
• intercellular joining
• cell to cell recognition

Question 15

What are two types of membrane proteins

Answer 15

Integral proteins

peripheral proteins

Question 16

Describe integral proteins

Answer 16

• Firmly inserted into membrane – most are trans membrane proteins the span the membrane
• have both hydrophobic areas that interact with lipids and hydrophilic areas that interact with water
• Function as transport proteins, enzymes, or receptors

Question 17

Describe the peripheral proteins

Answer 17

• Loosely attached to integral proteins
• include filaments or intracellular surface used for plasma membrane support
• function as enzymes, cell to cell connections, motor proteins for shape change during cell division and muscle contraction

Question 18

Describe how a membrane protein performs the task of transport

Answer 18

It could provide a hydrophilic channel across the membrane selective for a specific solute some transport proteins hydrolyze ATP as energy source to active Lee pump substances across the membrane

Question 19

Describe how a membrane protein may perform the task of receptors for signal transduction

Answer 19

Select membrane proteins exposed to the outside of the cell may have a binding site that fits a specific chemical messenger such as a hormone. When triggered this chemical messenger may cause a change in shape in the protein that initiates a chain of chemical reactions in the cell.

Question 20

Describe how a membrane protein may attach to the cytoskeleton and extracellular matrix.

Answer 20

Membrane proteins may anchor two elements of the cytoskeleton and the extracellular matrix hoping to maintain shape and fix the location of certain membrane proteins other membrane proteins play a role in cell movement or bind adjacent cells together

Question 21

Describe the enzymatic activity of certain membrane proteins

Answer 21

• The membrane protein may be an enzyme with an active site exposed to substances in the adjacent solution
• a team of several enzymes in a membrane may capitalize sequential steps of a metabolic pathway. For example one enzyme me catalase solute a into solute be and another enzyme will catalase solute be into solute see and continues until it becomes metabolized into solutes Z

Question 22

Describe how a membrane protein helps in intercellular joining

Answer 22

• membrane proteins may be hooked two adjacent cells in various kinds of intercellular junctions
  – some membrane proteins (cell adhesion molecules or cams) of this group provide temporary binding sites that guide cell migration and other cell to cell interactions

Question 23

How do you some membrane proteins perform cell to cell recognition

Answer 23

Some glycoproteins (Proteins bonded to short chains of sugar which help to make up the glycocalyx) serve as identification tags that are specifically recognized by other cells.

Question 24

What is the glycocalyx and what purpose does it serve

Answer 24

It consists of sugars carbohydrates sticking out of the cell surface
-some sugars are attached to lipids glycolipids and some to proteins glycoproteins

This serves as specific biological marker for cell to cell recognition and allows the immune system to recognize self versus non-self.
Every cell tape has a different pattern of this sugarcoating

Question 25

What are three ways cells can be bound together to form tissues and organs?

Answer 25

–Tight junctions –desmosomes –gap junctions

Question 26

Explain the characteristics of a tight junction

Answer 26

- These are integral proteins on adjacent cells fuse to form an in permeable junction that in circles the whole cell - prevent fluids in most molecules from moving in between cells for example stomach

Question 27

Explain desmosomes cell junctions

Answer 27

Rivet like cell junction formed when linker proteins of neighboring cells interlock like teeth of a zipper or Velcro-linker protein is anchored to its cell through thickened button like areas on inside of plasma membrane called plaques - keratin filaments connect plaques intracellularly for added anchoring strength – desmosomes allow give between cells reducing the possibility of tearing under tension

Question 28

What are connexons what do they do

Answer 28

Form the pore for a gap junction between the cytoplasm of two adjacent cells. This channel allows for bidirectional flow of ions and signaling molecules.

Question 29

What Are two ways substances move across the plasma membrane?

Answer 29

- Active processes where energy ATP is required | - passive processes were no energy is required

Question 30

Are two types of passive membrane transport

Answer 30

Diffusion and filtration

Question 31

Where does filtration normally occur

Answer 31

Usually occurs across capillary walls

Question 32

What influences the speed of diffusion

Answer 32

Size of the molecule and temperature

Question 33

How does the plasma membrane’s selectively permeable barriers affect diffusion?

Answer 33

They stop diffusion and create concentration gradients on either side

Question 34

What molecules are able to passively diffuse through membranes

Answer 34

- Lipid soluble and non-polar substances - very small molecules that can pass through membrane or membrane of the channels - larger molecules assisted by carrier molecules

Question 35

What will pass through via simple diffusion?

Answer 35

- Nonpolar lipid soluble hydrophobic substances diffuse directly through the phospholipid bilayer Oxygen, carbon dioxide, fat soluble vitamins

Question 36

What are the two types of facilitated diffusion?

Answer 36

- Carrier mediated facilitated diffusion | - channel mediated facilitated diffusion

Question 37

What are The carriers in carrier mediated facilitated diffusion and explain how it works

Answer 37

The carriers are transmembrane integral proteins and they transport specific polar molecules such as sugars and amino acids too large for membrane channels. Binding of molecule causes carrier to change shape moving the molecule in the process Binding is limited by the number of carriers present

Question 38

What are channel in the channel mediated facilitated diffusion and explain how it happens

Answer 38

Channels with aqueous filled cores are formed (aquaPorins) by transmembrane proteins -channels transport molecules such as ions or water down there concentration gradient. Specificity based on poor size and/or charge

Question 39

What are two types of channels in the channel mediated facilitated diffusion?

Answer 39

-Leakage channels always open -gated channels controlled by chemical or electrical signals

Question 40

What are two ways water diffuses via osmosis through the plasma membrane

Answer 40

- go to specific water channels called aquaPorins - Through the lipid bilayer even though it’s polar because it is so small it could still get through the non-polar phospholipid tails

Question 41

When does osmosis occur?

Answer 41

When water or other solvent concentration is different on the two sides of the membrane

Question 42

What is Osmolarity

Answer 42

It’s the measure of total concentration of solute particles

Question 43

What is hydrostatic pressure?

Answer 43

Pressure of water inside the cell pushing on the membrane

Question 44

What is Osmotic pressure

Answer 44

Tendency of water to move into a sell by osmosis the more solutes inside a cell the higher the osmotic pressure

Question 45

What is changing cell volume affect

Answer 45

Can disrupt cell function especially in neurons

Question 46

What is tonicity

Answer 46

The ability of a solution to change the shape or tone of cells by altering the cells internal water volume Example hypertonic solutions pull water out of the cells hypotonic solutions are never give in because it results in hemolysis