the cell

Question 1

what is the role of lysosomes?

Answer 1

they are sacs of digestive enzymes
- used for repair and removal of foreign matter
eg. white blood cells

Question 2

what is the negative feedback loop and give an example?

Answer 2

is pregnancy or blood clots

in pregnancy oxytocin is released to the uterus causing more contraction

Question 3

name 2 functions of the smooth endoplasmic reticulum ?

Answer 3

• calcium storage
  eg. skeletal muscle
• de-toxification
  eg. liver
• steroid production
  eg. ovaries, testes

Question 4

what do ribosomes and endoplasmic reticulum do?

Answer 4

ribosomes are responsible for making proteins. They read genetic instructions carried out from mRNA and assemble amino acids in the correct order to form a protein

there are two types of endoplasmic reticulum
-smooth and rough

smooth: involved lipid synthesis, detoxification, and calcium storage

rough: makes organelles, and transports proteins made by ribosomes, assists in folding
eg. insulin and digestive enzymes

Question 5

what is the function of the peroxisomes?

Answer 5

its found in the liver
they are known as oxidative enzymes

• helps in metabolism like beta oxidation, lipid synthesis
• and detoxify various waste products
• breaks down toxic substances like hydrogen peroxide and convert it into water and oxygen using an enzyme called catalase

Question 6

name three things that are controlled by homeostasis?

Answer 6

blood pH
blood volume
body temperature
blood pressure
water/electrolytes
o2/co2
nutrients and wastes

Question 7

What cells are multi-nucleated and why? Which cells have no nucleus?

Answer 7

muscle cells or skeletal muscle cells are multinucleated : why because they result from the fusion of many precursor cells called myoblasts, and having multiple nuclei allows the large muscle fibers to efficiently manage the high demand for protein synthesis and cellular repair across their length
and red blood cells have no nucleus to allows more space for hemoglobin and the protein that carries oxygen

Question 8

What cells will have many lysosomes?

Answer 8

white blood cells and liver cells

Question 9

Give an example of where are microtubules used in cell function.

Answer 9

they are used to transport secretory vesicles
form mitotic spindle during cell division

Question 10

What is the genetic theory of aging?

Answer 10

telomere shortening
- with each replication of DNA nucleotides are lost

Question 11

as we age what gradually happens to our cells?

Answer 11

our cells gradually deteriorate
- lose function
-cant respond to stress
- #of body cells decrease
- lose integrity of the extracellular components

Question 12

what are the structures making up the cell membrane?

Answer 12

• phospholipid bilayer (one end is hydrophilic and one end is hydrophobic) creates a semi-permeable membrane
• proteins:
  integral proteins- these are proteins that span across the membrane and act as channels, carriers, or receptors facilitating transport and communication
  peripheral proteins- outside surface of membrane, play role in signalling, structural support, and maintaining cells shape

cholesterol: are embedded within the phospholipid bilayer, they help stabilize the membranes fluidity making it less permeable to small water soluble molecules

carbohydrates: are often attached to proteins (glycoproteins) or lipids (glycolipids) on the extracellular surface of the membrane
- play a role in signaling, or cell recognition

glycoproteins: proteins that are attached to carbohydrate chains that are involved in cell recognition and immune response.

Glycolipids: lipids with attached carbohydrate chains that contribute to membrane stability and cell interactions

Question 13

what is the role of enzymes?

Answer 13

enzymes are typically proteins that act as a catalyst they speed up chemical reactions within the cell

• lower activation energy, reduce the activation energy for the reaction to occur which speeds up the reaction
• catalyses metabolism

Question 14

How do glucose molecules move across the membrane?

Answer 14

facilitated transport/ facilitated diffusion which is the process in which a carrier protein moves glucose from high concentration to low.

• this process does not require ATP

Question 15

How do Na+ molecules move across the membrane?

Answer 15

• this uses active transport either secondary or primary
  primary uses:
  -which uses atp cus you are going against the concentration gradient
  low to high

Question 16

what is secondary active transport

Answer 16

• does not directly use atp but instead is powered by the [ ] gradient of one solute
• moved solute against their concentration gradient

symport: move in the same direction across the membrane

antiport: move in opposite directions across the membrane

Question 17

what are three functions of a protein?

Answer 17

proteins can act as enzymes which speed up chemical reactions like digestion or metabolism

structural support

transport and storage

Question 18

What is osmosis and diffusion?

Answer 18

diffusion: movement of molecules from an area of higher concentration to an area of lower concentration
- no ATP required

osmosis: Specific type of diffusion that involves the movement of water molecules across a semi-permeable membrane

water moves from an area of lower solute and high water concentration to an area of high solute concentration and low water concentration.

Question 19

What is exocytosis?

Answer 19

this is a process of active transport known as vesicular transport

• exocytosis is a process by which cells transport materials out of the cell. it involves the fusion of a vesicle (a small membrane-bound sac) with the cell membrane to release contents into the extracellular space

Question 20

what is endocytosis?

Answer 20

process in which cells take in materials from the outside environment by engulfing with their cell membrane, forming a vesicle that brings the substance into the cell.

Question 21

ligand-mediated endocytosis

Answer 21

also known as a receptor-mediated endocytosis is a specific process where a cell absorbs substances from outside by binding them to a specific receptor on its surface. Once the ligand or the susbstance binds to the receptor, the cell membrane folds inward, forming a vesicle that brings the ligand receptor complex into the cell
eg. moves iron and antibodies

Question 22

what is phagocytosis?

Answer 22

type of endocytosis where a cell engulfs large particles, such as debris bacteria and such then comes into the membrane to form a vesicle called a phagosome.

• the phagosome then fuses with a lysosome, where enzymes break down and digest the engulfed material.
• this is essential for immune response in white blood cells then they remove pathogens and cellular debris.

Question 23

what is pinocytosis?

Answer 23

cell absorbs water molecules that are present in the extracellular fluid, it helps the cell take in nutrients, ions, and other molecules from its environment

Question 24

What factors determine the rate of diffusion?

Answer 24

1. concentration gradient - the greater the difference in concentration between two areas, the faster the rate of diffusion
   - molecules move more quickly from high to low concentration when the gradient is steep
2. temperature- higher temp the more kinetic energy of molecules
3. diffusion distance - the shorter the distance over which diffusion occurs, the faster the rate

Question 25

What is tonicity? How does this affect osmosis?

Answer 25

• ability of a solution surrounding a cell to cause that cell to gain or lose water.
  tonicity affcets the direction and extent of osmosis, the movement of water across a semi-permeable membrane

1. isotonic solution
   [ ] is equal inside and outside the cell
   osmosis: there is no net movement and the cell remains the same
2. hypotonic solution: [ ] of solutes outside the cell is lower than the inside of the cell

osmosis: water moves into the cell, causing it to swell and possibly burst (hymolasas) if too much water enters

3. hypertonic solution: the [ ] of solutes outside the cell is higher than inside the cell
   osmosis: water moves out of the cell, causing it to shrink

Question 26

Does water move towards a hypertonic or hypotonic solution?

Answer 26

Water moves towards the area with more solutes (hypertonic) because it wants to “even out” the concentration. In other words, water moves to where there is less water and more dissolved stuff.

Question 27

What is the role of the glycocalyx?

Answer 27

it serves as a protective adhesive, and recognition layer on the cell surface, playing a important role for communication
- its a sugar rich coating that surrounds the cell membrane, and consists of carbohydrates attaches to proteins (glycoproteins) and lipids (glycolipids) on the cell surface

Question 28

What is co-transport and counter-transport?

Answer 28

cotransport is known as symport in secondary transport
and counter-transport is antiport in secondary transport

Question 29

what are the three second messengers ?

Answer 29

cAMP- activates protein kinase
rapid amplification
CALCIUM- activated IP3 causes release of ca2+ from ER
DAG and IP3 activate enzymes
CALMODULIN

Question 30

what are the three types of receptors that bind ligands?

Answer 30

G-protein coupled receptors :
get instruction from outside and they dont make changes themselves but they signal the inside of the cell to create cellular responses
ex. adrenaline, dopamine

channel-linked receptors: ligand binds gate opens ions flow through changes electrical activity in cell

enzymatic receptors: sets off a chain reaction in the cell, domino affect amplifying signal and gets bigger response
- it phosphorylates (adds phosphate) other enzymes within the cell, can alter enzymatic activity