Bio - Cells

Question 1

What six things make up a living organism?

Answer 1

• Need energy
• Produce waste
• Respond and adapt to environment
• Reproduce
• Grow
• Made up of cells

Question 2

Explain cell theory

Answer 2

• All organisms are composed of 1 or more cells
• Cell is the smallest functional unit of life
• All cells are produced from other cells

Question 3

What is abiogenesis? How long was this theory accepted for?

Answer 3

Abiogenesis is the theory that life could arise from non-living matter. It was widely accepted for over 2000 years.

Question 4

What is biogenesis?

Answer 4

Biogenesis is the theory that life could arise only from other living organisms.

Question 5

Describe the composition of the cell membrane

Answer 5

• Composed of a double layer of phospholipids
• Proteins, lipids, and carbohydrates are embedded between the layers

Question 6

What are the two main functions of a cell membrane?

Answer 6

1. Biological barrier to prevent some substances from entering the cell in any way and surround each organelle to prevent unwanted chemical reactions.
2. Selective filter to allow some, but not all, materials to cross.

Question 7

What properties does a cell membrane have?

Answer 7

• All material entering & exiting the cell must cross the cell membrane
• Can change according to the cell’s needs
• Fluid and flexible, “fluid-mosaic” model

Question 8

What is the phospholipid bilayer? What is it made out of?

Answer 8

Phospholipids:

• Each molecule has a head and a tail-

Heads are hydrophilic (water loving), dissolves in water, polar

Tails are hydrophobic (water fearing), H₂O molecules push away tail, not polar

• Heads face out, tails are sandwiched between
• Two layers (bilayer)

Question 9

What does Brownian motion state?

Answer 9

“In liquid or air, particles are in a constant, random motion.”

Question 10

What is a concentration gradient? Which way are you moving if molecules go from a high concentration to a low concentration? How about a low conecntration to a high concentration?

Answer 10

Concentration Gradient:

Difference in concentration

High concentration to low concentration moving down

Low concentration to high concentration moving up

Question 11

What is equilibrium? What 3(ish) things happen?

Answer 11

Equilibrium:

• Molecules are evenly distributed on either side of cell membrane
• Overall (net) flow does not change
• Do not stop moving after reaching balance

Question 12

What are three ways molecules can be transported across the cell membrane in order to reach equilibrium?

Answer 12

1. Passive transport (Diffusion, osmosis, facilitated diffusion)
2. Active Transport
3. Endo- and exocytosis

Question 13

What is passive transport? What is it used for? What types are there?

Answer 13

• Does not require energy to move across membrane
• Used for molecules too large to pass through membrane or charged particles

Types:

1. Diffusion - movement of particles from high to low
2. Osmosis - movement of water molecules from high to low // Less solute, more water. More solute, less water //
3. Facilitated diffusion -

• Carrier proteins - change shape to allow certain molecules (ie. sugar) to pass
• Channel proteins - charged ions in and out of cell (ie. Na⁺), must be opened

Question 14

What is active transport? What is it used for?

Answer 14

• Requires energy (ATP) from cell to move particles from low concentration to high concentration

(against concentration gradient)

• Transport proteins bind to materials & change shape to move across membrane

Used by:

• Plant root cells to take in minerals from soil
• Remove waste in cells

Question 15

What is endocytosis? When is it used? What direction does it go? What types are there?

Answer 15

• Membrane folds in, forms a pocket that turns into vesicle for transport
• Used when molecules cannot be moved by passive or active transport
• Into the cell

Types:

1. Phagocytosis: “cell-eating”, ingest food/other solid materials
2. Pinocytosis: “cell-drinking” ingest droplets of water/other fluids
3. Receptor-mediated endocytosis: take in molecules (ie cholosterol), receptor on cell identies item and binds it to trigger endoycytosis

Question 16

What is exocytosis? What is it used for? What direction does it go?

Answer 16

• Allows materials stored in vesicles/vacuoles to exit cell
• Used to release waste
• Out of the cell

Question 17

What happens when the size of a cell increases?

Answer 17

Size increases, surface area to volume ratio decrease.

Question 18

Why is a large volume bad?

Answer 18

• More energy is used to trasport materials through the cell because they have to go farther
• If the surface area is smaller than the volume, all parts of the cell won’t get nutrients they need

Question 19

What surface area to volume ratio does the cell want?

Answer 19

The cell wants a high surface area to volume ratio because:

• The cell can get more nutrients & O₂
• It is easier ot exchange food, waste, O₂ and CO₂ with their surroundings

Large surface area to volume ratio is better!

Question 20

What is a hypotonic solution?

Answer 20

More water molecules and less solute particles in comparison to a cell

Question 21

What is a hypertonic solution?

Answer 21

Less water molecules and more solute particles

Question 22

What is a isotonic solution?

Answer 22

• Concentration outside and inside the cell is equal
• Rate that water flows into the cell & out of the cell is the same

Question 23

Define lysis (+provide an example)

Answer 23

Cells gain so much water that they burst

ie. Animal cells cannot reach equilibrium in distilled water, water is flowing in at too fast of a rate

Question 24

Define crenation (+provide an example)

Answer 24

Cells lose so much water that they shrink/shrivel up then die

ie. Animal cells cannot reach equilibrium in strong salt water, water is flowing out to balance at a too fast of a rate

Question 25

Do cells stop growing?

Answer 25

Cells will only grow to a certain size then stop, it takes too much energy to support a huge cell.

Question 26

Who first tested abiogenesis?

Answer 26

Francisco Redi used experiments to test this theory using meat in two jars & one covered.

Question 27

What is the nucleus? What is its function?

Answer 27

The nucleus is the most visible part on the animal cell, its function is to control the cell's activities.

Question 28

What is encoded in the nucleus?

Answer 28

The cell's genes (DNA) is encoded in the nucleus

Question 29

How do messenger molecules exit the nucleus? What happens once they're out?

Answer 29

Through the nuclear pores in the nucleus. The messenger molecules then attach themselves to ribosomes, which translate the information into proteins.

Question 30

What organelles are only in plants? Explain their functions

Answer 30

Cell Wall: * Made out of cellulose, rigid and supportive Chloroplasts: * Organelles of photosynthesis * Have two layers of membranes: inner layer of flattened sacs & second layer encloses it * Inner membrane includes cholrophyll: absorbs Sun energy and converts into chemical energy that creates sugars from CO₂ and H₂O

Question 31

Explain the development of the cell theory

Answer 31

Robert Hooke: * observed dead cork cells * came up with word "cells" Antony van Leeuwenhoek: * 1st microscope * studied blood cells, pond water, matter scraped from teeth Schleiden and Swann: * 1st to see nuclei in plant cells & animal tissue Rudolf Virchow: * cells divide to produce more cells

Question 32

What is cancer?

Answer 32

Cancer is the damage to cells, which change DNA causing mutations

Question 33

What is a virus?

Answer 33

A virus is genetic material inside a protein coat, however they cannot replicate themselves. They infect by taking over host (living) cells.

Question 34

What do viruses and prions have in common?

Answer 34

They do not have independent life functions, therefore not considered functional units of life

Question 35

What is a prion?

Answer 35

A prion is a protein that converts from its normal form into a harmful particle.

Question 36

What is the endoplasmic recticulum?

Answer 36

Network of folded membranes and tubes connected with the nucleus, includes two types: Rough Endoplasmic Recticulum: * Has ribosomes, proteins created by them are packaged into vesicles. Smooth Endoplasmic Recticulum: * No ribosomes * Combine lipids and packages proteins/lipids into vesicles

Question 37

What is the golgi apparatus? What does it do?

Answer 37

* Molecules from endoplasmic recticulum are modified by enzymes * Sorts and repackages molecules into vesicles * Produces lysosomes

Question 38

What does mitochondria do?

Answer 38

* "Powerhouse" of the cell * Chemical reactions convert energy from food molecules into energy the cell can use * Reactions happen on folded membranes inside the mitochondria

Question 39

What do vacuoles do? What is the difference between vacuoles in plants and vacuoles in animals?

Answer 39

* Store water, food, minerals, and waste * *Plants* have a large central vacuole to regulate water in the cell * *Animals* have many smaller vacuoles

Question 40

What are stem cells?

Answer 40

Stem cels are "blank slate" cells: * divide to produce any type of cell in the body * may hold the cure for many diseases.

Question 41

What organelles are only in animals?

Answer 41

Lysosomes: * **Break down particles** with digestive enzymes * Can fuse with vesicles Centrioles: * Cylindrical structures outside nucleus * **Crucial during cell division**, move correct genetic material into each new cell.

Question 42

What is cytoplasm? What is it made out of?

Answer 42

Cytoplasm * Jelly-like substance that fills cell & suspends contents * Made up of **+50% water**

Question 43

Name & contrast the organelles of a plant and animal cell

Answer 43

Organelles in both: Cell membrane, nucleus, endoplasmic recticulum, golgi apparatus, mitochondria, vacuoles Plants: Cell wall and cholorplats Animals: Lysosomes and centiroles