Cellular Level Of Organization

Question 1

What is the cell?

Answer 1

• basic structural and functional unit of the body
  
  • can perform all basic life functions

Question 2

What are the principal parts of the cell?

Answer 2

1. Cell Membrane/Plasma Membrane/Plasmalemma
2. Cytoplasm
3. Nucleus

Question 3

Cell Membrane/Plasma Membrane/Plasmalemma

Answer 3

• Boundary between the inside and outside of a cell.
• Composed of:
  
  1. Phospholipid belayer
  2. Cholesterol
  3. Membrane Proteins
  4. Membrane Carbohydrates
  5. Microvilli
     1 & 3. Fluid Mosaic Model

Question 4

Phospholipid Bilayer

Answer 4

• phosphate head group (HYDROPHILIC -> loves water)
• FA tails (HYDROPHOBIC -> hates water)
• divides ICF and ECF
  
  • Intracellular Fluid (ICF) = Inside cell
  • Extracellular Fluid (ECF) = outside cell

Question 5

Cholesterol

Answer 5

• Scattered throughout membrane
• Adds stability to the cell membrane

Question 6

Membrane Proteins

Answer 6

• 2 types:
  
  • integral protein
  • peripheral protein

Question 7

What are the functions of membrane proteins?

Answer 7

• enzymes
• transporters
• channels
• receptors
• anchors
• identity markers (for immune system

Question 8

What is integral proteins?

Answer 8

• integrated within the membrane, therefore, have a hydrophobic region
• some extend across entire membrane, and are called transmembrane proteins

Question 9

What is peripheral proteins?

Answer 9

• attached to either surface of integral proteins I.e. on the periphery of the cell membrane

Question 10

Membrane Carbohydrate

Answer 10

• only on outer surface
• bound to protein (glycoproteins) or lipids (glycolipids)
• Function:
  
  • cell recognition e.g. sperm recognize egg cell
  • anchor cells together

Question 11

Microvilli

Answer 11

• small projections of cell membrane
• function is to increase surface area ( helps absorb nutrients)
• best seen on cells of the small intestine and kidney

Question 12

Fluid Mosaic Model of the Cell Membrane

Answer 12

• fluid = membrane constituents can move around (phospholipids and some proteins)
• Mosaic = proteins dot surface like tiles in a mosaic

Question 13

What is the Cytoplasm?

Answer 13

• AREA between the inside of the cell membrane and the outside of the nucleus

Question 14

What are the 2 divisions of Cytoplasm?

Answer 14

1. Cytosol = gel-like intracellular fluid
2. Organelles

Question 15

What is Cytosol?

Answer 15

• Contains water, ions, and a suspension of carbohydrates, proteins, and lipids
• May contain inclusions e.g. Melanin (pigment, glycogen (stored glucose)

Question 16

What is Organelles?

Answer 16

• Structures that perform a specific function and are essential for life
• are either:
  
  • Non-membranous (in direct contact with cytosol)
  • Membranous (surrounded by membrane that isolates them from cytosol)

Question 17

What are non -membranous organelles?

Answer 17

1. Ribosomes
2. Centrosomes
3. Cytoskeleton

Question 18

Ribosomes

Answer 18

• Sites for protein synthesis
• Contains ribosomal (rRNA) and proteins

Question 19

What Two Types Can Ribosome Be?

Answer 19

1. Free ribosomes - float in cytosol and make proteins that go to cytosol, mitochondria, and/or nucleus
2. Attached to endoplasmic Reticulum (ER) - make proteins destined for all other sites

Question 20

Centrosomes

Answer 20

• Consist of 2 components: a pair of centrioles and the pericentriolar matrix
• Organizing centres for microtubules
  
  • Spindle apparatus (for cell division)
  • Organizes cytoskeleton

Question 21

Cytoskeleton

Answer 21

• All types are for structural support (for cell shape) and are formed from proteins
• important in cell movement, cell division, movement/anchoring of organelles and proteins (e.g. receptors, enzymes)

Question 22

What are the 3 types of Cytoskeleton?

Answer 22

1. Microfilaments
2. Intermediate Filaments
3. Microtubules

Question 23

what is Microfilaments and it’s function?

Answer 23

• Made of actin
• Function: Muscle contraction (with myosin), cell locomotion and cytokinesis

Question 24

Intermediate Filaments

Answer 24

Composition is tissue specific
- e.g. Keratin

Question 25

what is Microtubules and it's function?

Answer 25

- Hollow tubes made of tubulin - Function: - Form: - Centrioles - Spindle Apparatus - Cilia (short) - Flagella (long) - Move or secure organelles in place

Question 26

What are Membranous organelles?

Answer 26

1. Mitochondria 2. Endoplasmic Reticulum (ER) 3. Golgi Apparatus/Complex 4. Lysosomes

Question 27

Mitochondria

Answer 27

- Site of ATP synthesis - Contains own DNA, RNA, and proteins - have a double membrane

Question 28

Endoplasmic Reticulum (ER)

Answer 28

- Membranous network throughout cytoplasm - 2 types: 1. Rough ER (RER) 2. Smooth ER (SER)

Question 29

Rough ER (RER)

Answer 29

- Ribosomes attached - synthesis of secretory, lysosomal and membrane proteins

Question 30

Smooth ER (SER)

Answer 30

- Lacks attached ribosomes - Continuous with RER - Synthesizes lipids and steroid hormones

Question 31

Golgi Apparatus/Complex

Answer 31

- Stacks of membrane discs - modifies proteins (e.g. trims or adds carbs and lipids), sorts, packages, and delivers them to cell membrane, lysosomes, or for secretion (cellular post office))

Question 32

Lysosomes

Answer 32

- Filled with digestive enzymes - Digest bacteria, viruses, worn-out organelles (clean up function)

Question 33

What is the Nucleus?

Answer 33

- Largest membranous organelle - cell control centre - cells may have 1 or more nuclei

Question 34

What are the 3 parts of the nucleus?

Answer 34

1. nuclear envelope 2. Nucleolus (>1 in some plants) 3. Chromosomes/chromatids

Question 35

Nuclear Envelope

Answer 35

- Double membrane with nuclear pores - Connected to ER

Question 36

Nucleolus (>1 in some plants)

Answer 36

- Non-membranous - Dense (less light gets through) region of DNA, RNA, and proteins where ribosomes are made and assembled

Question 37

Chromosomes/Chromatids

Answer 37

- Contain DNA and histone proteins - Can be: 1. Dispersed = Chromatin - DNA uncoiled and not individually visible - In this form most of the time (when cell is not dividing) 2. Condensed and individually visible - Found in dividing cells (during mitosis/meiosis)