Topic 1-5: Cell Structure, Function, Movement & Communication

Question 1

Explain the Cell Theory

Answer 1

1. All orgnisms are made up of cells
2. Cells are the basic unit of life
3. Cells come from pre-existing cells that have multiplied

Question 2

Describe the 2 types of cells

Answer 2

Prokaryotes: no nucleus, no cytoskeleton, no cytoplasmic organelles, singular circular DNA molecule

Eukaryotes: nucleus, cytoskeleton, and cytoplasmic organelles are present; multiple linear DNA molecule

Question 3

What are tissues?

Answer 3

Complex organizational arrangments of cells that are similar in structure and function

Question 4

Groups of tissues form what?

Answer 4

Organs, containing different combinations of tissues types

Question 5

Groups of cells form

Answer 5

Cells –> tissues –> organs –> organ systems

Question 6

What is the process in which cells need to die in order to form new cells?

Answer 6

Apoptosis: programmed cell death

Question 7

Break down the water component in our body

Answer 7

2/3 is intracellular fluid (ICF)
1/3 is extracellular fluid (ECF) = 20% blood and 80% interstitial fluid

Question 8

Functions of nucleus

Answer 8

The control center of the factory “cell”. It stores chromosomes which contains DNA, the information needed for cell processes as well as making proteins.

Question 9

Describe nucleolus

Answer 9

A site where RNA transcription and ribosomes biogenesis happen

Question 10

What are the differences between rough and smooth endoplasmic reticulum?

Answer 10

Rough ER: synthesise and fold ribosomes + proteins

Smooth ER: lipid and steroid hormone production

Question 11

What organelle is responsible for distributing proteins?

Answer 11

Golgi complex is responsible for processing and sorting proteins from ER to the right destinations by vesicles

Question 12

What organelle is the power house of cells? How?

Answer 12

Mitochondria which contains its own DNA and replicates by fission makes ATP used as energy currency for cell’s activities

Question 13

What organelle disposes waste in cells?

Answer 13

Lysosomes are acidic organelles that can break down and dispose waste

Question 14

What is the function of cytoskeleton?

Answer 14

Cytoskeleton includes filaments and tubules which are responsible for structure, support, and transport

Question 15

What structure is the plasma membrance?

Answer 15

The plasma membrance is a phospholipid bilayer (hydrophilic heads and hydrophobic tails)

Question 16

What substances can and cannot move through the plasma membrane?

Answer 16

The plasmas membrane is permeable to non-polar molecules like O2, CO2, H2O, other small uncharged particles.

Impermeable to most essential molecules and ions, small hydrophilic molecules; and maromolecules.

Question 17

What are diffusion and osmosis?

Answer 17

Diffusion is the movement of substances from higher to lower concentration which happens over time until equilibrium is reached.

Osmosis is water flowing through a semipermeable membrane to another aqueous compartment containing higher solute concentration (follow concentration gradients)

Question 18

What is tonicity?

Answer 18

The ability of the extracellular solution to make water move into or out of cell to reach equilibrium by osmosis

Question 19

3 types of tonicity

Answer 19

Isotonic: equal solute concentration –> continous osmosis to maintain equilibrium

Hypertonic: lower solute concentration than outside –> water flow out of cell –> shrink

Hypotonic: higher solute concentration than outside –> water flow into cell –> swell

Question 20

What are included in the membrance in order to transport bigger molecules?

Answer 20

“Transmembrane” or integral membrane proteins

Question 21

What are the functions of proteins located within the plasma membrane?

Answer 21

These proteins interact with different stuffs outside and inside the cells as well as forming pores (or channels) for facilitated diffusion and active transport.

Question 22

What types of molecules or stuffs that require channels to move in and out of the cell?

Answer 22

Ions, proteins, macromolecules

Question 23

What channels are needed to transport a huge amount of water we take in everyday?

Answer 23

Aquaporins, which appear everywhere in our body, dynamically regulate the amount of water present. These channels help to increase the amount of water taken up.

Question 24

Explain the differences between facilitated diffusion and active transport

Answer 24

Facilitated diffusion: molecules move from higher to lower concentration without taking up any ATP (follow the concentration gradients)

Active transport: molecules use ATP to move from lower to higher concentration (against the concentration gradients)

Question 25

What happens when ions pass through transmembrane proteins?

Answer 25

When ions move through the channels, the charge inside and outside of the cell become different, creating electrochemical potential difference. That why we say ions channels conduct charge.

Question 26

Explain the process of the Sodium-Potassium pump and its functions

Answer 26

The Sodium-Potassium Pump (or Na-KATPase) pumps 3 Na+ out of the cell and 2 K+ in to the cell ==> create a electrochemical gradients (negative membrane potential)

This helps to maintain a stable resting membrane potential, which is essential for many physiological processes and transport.

Question 27

What is the role of facilitated diffusion in substances movement?

Answer 27

Facilitated diffusion regulated the movement of nutrients (glucose, amino acids, etc.) across membrane

Question 28

Explain endocytosis and exocytosis

Answer 28

endocytosis: transporting of materials into the cytoplasm using vesicles

exocytosis: transporting of materials out of the cytoplasm using vesicles (substances secretion)

Question 29

Explain the concept of homeostasis

Answer 29

Body’s tendency to maintain internal consistency by counteracting change

Question 30

Explain the differences between negative and positive feedback loops

Answer 30

Negative feedback loops: counteract change to maintain equilibrium, return to set points

Positive feedback loops: amplify first stimulus and move further away from the set points

Question 31

What is the endocrine system?

Answer 31

A slow chemical-based messaging system in which a set of glands secrete hormones directly into the bloodstream. These hormones will travel to all parts of the body, but impact only cells that contain receptors for that hormone.

Question 32

How many types of glands are there?

Answer 32

2 types
Exocrine glands: glands that have ducts to bring their secretory matter to a surface

Endocrine glands: ductless gland that internally secrete hormones into bloodstream or lymph

Question 33

What is hormone?

Answer 33

A hormone is a chemical messenger made by glands, which travel in the bloodstream to target organs and trigger a response.

Question 34

Describe the function of hormones

Answer 34

1. Reproduction, growth, development
2. Maintenance of internal environment
3. Energy production, utilization, storage

Question 35

What is a ligand and a receptor?

Answer 35

A ligand is a signaling molecule, so all hormones are glands.

A receptor can be found in the cell membrane or inside the cell, to which the hormone binds and trigger a cell process.

Question 36

Describe the characteristics of a receptor

Answer 36

1. High affinity interaction with ligands (tight binding)
2. High specificity for ligands (only bind to one specific ligand)
3. Have a specific distribution patterns

Question 37

Desribe the signaling process

Answer 37

A process of responsing to an external stimulus and making decisions regarding cell processes

Question 38

Describe the differences between water soluable hormones and lipid soluable hormones

Answer 38

Water soluable hormones are peptide hormones and cannot get through the cell membrane, so they have to bind to a membrane receptors which will trigger a signal cascade and amplification.

Lipid soluable hormones can diffuse through membrane, then bind to a receptor inside the cell and change gene expression.

Question 39

Describe signal amplification

Answer 39

A process in which the first signal activated by first messenger binding the receptor will be relayed and intensifies during intracellular reactions.

Question 40

Describe phosphorylation cascade

Answer 40

Phosphorylation cascade is a series of signalling events in which one protein after another become phosphorylated and then, activate the targeted protein.

Question 41

Compare first and second messenger

Answer 41

First messenger: extracellular substances which, through receptor-binding, can trigger intracellular processes

Second messenger: (like intracellular ligands) intracellular substances that bring signals from the receptors to to targeted proteins, mediated by kinases enzymes

Question 42

What makes a second messenger?

Answer 42

1. Has to be low amount in resting state
2. Regulated synthesis
3. Regulated destruction
4. Act through other proteins

Question 43

Describe steroid hormones and its functions

Answer 43

Steroid hormones are derivatives of cholesterols, so they can enter cell without membrane receptors (but still bind to a hormone receptor inside the cell)
These hormones cause growth (via protein production), regulate endometrial growth and menstruation.

Question 44

What is an oxytocin?

Answer 44

Oxytocin is hormone involved in uterine contraction and breast milk ejection.

Question 45

What is ADH?

Answer 45

Antidiuretic hormone which prevents water loss through kidneys
This hormone is released when
- blood osmolarity increases
- blood pressure decreases
- blood volume decreases