Review of Structure + Function

Question 1

What is Cell Theory?

Answer 1

1. All living organisms are composed of one or more cells
2. The cell is the basic unit of struture and organization in organisms
3. All cells come from pre-existing cells

Question 2

Describe prokaryotes.

Answer 2

• No true nucleus or any membrane bound organelles
• Smaller cells
• Always unicellular
• Binary Fission
• Always asexual
• Example: bacteria

Question 3

Descrive eukaryotes.

Answer 3

• Has a nucleus and membrane bound oganelles
• Large cells
• Usually multicellular
• Mitosis / Meiosis
• Sexual or asexual
• Example: plant and animal

Question 4

What is the primary function of epithelial cells?

Answer 4

Form protective barriers in tissues and may be specialized to absorb or secrete specific compounds.

Question 5

What is the primary function of muscle cells?

Answer 5

Responsible for movment of the skeleton, heart and many internal organs.

Question 6

What is the primary function of nerve cells?

Answer 6

conduct electrical signals throughout the body, control contraction of muscles, responsible for the five senses.

Question 7

What is the primary function of connective tissue cells?

Answer 7

Create extracellular material that holds cells together in tissue, may be specialized to absorb or resist external forces.

Question 8

What is the primary function of bone cells?

Answer 8

Form the bones of the skeletal system to give strength and support to the body - very tough cells.

Question 9

What is the primary function of secretory cells?

Answer 9

These cells form glands and, as their name implies, are secretory.

Question 10

What is the primary function of adipose cells?

Answer 10

These are fat cells located throughout the body to store fat.

Question 11

What is the primary function of red blood cells?

Answer 11

These are cells formed primarily in the bone marrow and released into the circulation where they move throughout the body. They have limited life spans and must be continuously replaced.

Question 12

Define hydrophilic.

Answer 12

“Water-liking” - attracted to water.

Question 13

Define hydrophobic.

Answer 13

“Water fearing” - molecules that try and keep away from water.

Question 14

What is the significance of water and carbon in the cell?

Answer 14

Nonpolar carbon-based structures are attracted to each other and repel water as much as possible. This is a key aspect that in part, allows a cell to form membranes and subcellular compartmentalization.

Question 15

What are the characteristics of water that make it ideal for supporting life?

Answer 15

1. What is liquid at room temperature.
   - Due to high heat of vaporization and specific heat index; a great deal of energy is required to raise the temperature of water
2. Water is a polar molecule
   - the oxygen atom of water is slightly negative, while the hydrogen atoms are slightly positive
   - H2O molecules form weak but signifant hydrogen bonds
3. Water is more dense as a liquid, not a solid
   - This is why ice can float in liquid water
4. Water has a high specific heat capacity
   - Water has the hightest specific heat capacity of any liquid present within the common conditions of the Earth’s surface - meaning it takes a large amount of heat to raise the temperature of water
5. Water has a high heat of vaporization
   - The quantity of heat that must be absorbed for a liquid to vaporize to a gas

Question 16

How does water support life?

Answer 16

• Hydrogen bonding characteristics inherent to H2O
• Dissolution of other molecules essential for life
• Provides an environment that facilitates the complex network of reactions that support the chemical basis of life
• Ice is less dense than water, ensuring that water-based habitats remain habitable and sheltered when the eath’s ambient temperayure drops below freezing
• High heat capacity acts as a massive stabilizer for thermal fluctuations

Question 17

How does water support cells?

Answer 17

1. The polar properties of water make an excellent solvent. This facilitates the delivery of nutrients and removal of wastes, and provides an environment that allows cells to exist within a network by facilitating the movement of chemical messengers within and between cells
2. The high specific heat capacity of water allows for thermoregulation by acting as a heat sink for the many chemical reactions that occur within cells, as well as the exchange of heat between liquid and air. This is critical for warm-blooded organisms, such as humans, that must regulate their body temperature.

Question 18

Why is carbon a building back of cellular molecules?

Answer 18

• It is small and can form up to 4 covalent bonds
• This flexibility in bond formation allows it to form a large variety of molecules such as: lipids, carbohydrates, amino acids and proteins, and nucleotides.

Question 19

What are the properties of lipids?

Answer 19

• Lipids are oils and fats
• They are made of hydrocarbon chains, and are usually quire hydrophobic and insoluble in water
• They can be hydrophillic in certain sections

Question 20

What are examples of lipids?

Answer 20

1. Cholesterol: regulates cell membrane fluidity and is a biological precursor for compounds such as steroid hormones, bile acids, and certain vitamins
2. Phospholipids: an ampipathic lipid that forms cell membranes. They have a hydrophillic head and a hydrophobic tail that enables them to form the lipid bilayer of cells.
3. Triglycerides: the main component of body fat in animals and how we store energy

Question 21

What are the properties of carbohydrates?

Answer 21

• They are composed of carbon and H2O
• The simple building block of carbohydrates are sugars
• Monosaccharides: single carbohydrate molecules containing only carbon, hydrogen and oxygen
• Diasaccharides: two monos - bonded together with a glycosidic bond
• Oligo-and Poly- saccharides: 3 to 10 monosaccharides linked together

Question 22

What are the nucleotides?

Answer 22

• Building blocks of DNA, RNA and ATP

- Composed of: a base, a 5-carbon sugar and at least one phosphate group

Question 23

What are amino acids?

Answer 23

Monomers composed of a carboxylic acid group and an amino group with a side group that varies between amino acid types - also known as the R group

Question 24

What are proteins?

Answer 24

Proteins are made up of long chains of amino acids help together by peptide bonds. These polypeptides fold into a 3D structure that is required for protein function. There are thousands of different types of proteins in a cell, each accomplishing vastly different tasks.

Question 25

Using the Eukaryopolis example, detail the cell organelles.

Answer 25

1. Plasma membrane (city limits and border police): keeps the cells organelles contained and regulates what can come in or leave the cell
2. The nucleus (Laws of Eukaryopolis): the laws are stored in the nucleus as DNA
   - Since the nucleus has such an important role, it is essential that it is protected from other cell processes. Here are some ways it isolates itself:
   - -> A special double layer membrane
   - -> Very selective nuclear pores
   - -> A unique cytoplasm
3. Mitochondria (power plants): they produce energy for the cell to use in all of its processes - this energy is produced in the form of ATP, which can be thought as cellular currency
4. Endoplasmic Reticulum and Golgi Apparatus (highway system and post office): ER carries molecules around the cell and the golgi processes and packages proteins before sending them off to different parts of the city
5. Smaller, Membrane Bound Organelles (waste treatment plants):
   - Lysosomes: break down waste and debris as well as digest proteins, lipids and nucleic acids into basic building blocks
   - Endosomes: sort and begin to break down waste material before it reaches lysosomes
   - Peroxisomes: breakdown of hydrogen peroxide
6. Cytoskeleton (steel girdles that hold the city together): stabilize the membrane (structural filaments) against deformations and can even generate force (motor filaments)