L1.2 Cell Structure & Function

Question 1

what are the three compartments of a cell?

Answer 1

nucleus, cytoplasm, plasma membrane

Question 2

what is the function of the nucleus?

Answer 2

control centre for the cell (controls protein synthesis), controls DNA

Question 3

explain the process of DNA –> RNA –> Proteins

Answer 3

the DNA (deoxyribonucleic acid) is the genetic material, the mRNA (messenger ribonucleic acid) copies the instructions from. the DNA and goes through the nuclear pores and into the cytoplasm which produces PROTEINS (carries our biological functions)

Question 4

what are ribosomes? and types of ribosomes?

Answer 4

ribosomes are needed for protein synthesis

types: free ribosomes and bound ribosomes

Question 5

explain the difference between free and bound ribosomes

Answer 5

free ribosomes: floating inside the cell, suspended in cytosol and proteins that function in the cytosol
bound ribosomes: bound to endoplasmic reticulum, proteins that function in membrane, within an organelle, outside of the cell

Question 6

what does the cytoplasm consist of?

Answer 6

organelles, cytosol, cytoskeleton

Question 7

what are the types of cytoplasm organelles?

Answer 7

nucleus, endoplasmic reticulum, golgi complex, lysosomes, peroxisomes, mitochondria

Question 8

what is endoplasmic reticulum? and types?

Answer 8

extensive network of membranes joining the nucleus

types: rough ER, smooth ER

Question 9

what is rough endoplasmic reticulum?

Answer 9

covered in rough ribosomes, proteins are made at the rough ER, act as a membrane factory

Question 10

what is smooth endoplasmic reticulum?

Answer 10

packages and transports proteins (from Rough ER) to the golgi complex in transport vesicle. has specialised functions in particular cells e.g. detoxification (liver and kidneys), making steroid based hormones (e.g. testes), releasing calcium for muscle contraction (skeletal and cardiac muscle)

Question 11

what is the golgi complex? and its function?

Answer 11

series of curved sacs
the golgi complex accepts transport vesicles from the ER for further processing
proteins are modified and shipped to their final destination- outside the cell, to the various membranes, to the organelles

Question 12

what are lysomes and peroxisomes? and their function?

Answer 12

both: membrane bound vesicles containing enzymes
lysosomes function: breakdown organic material inside the cell (e.g. bacteria, old organelles)
peroxisomes function: degrade toxic molecules inside the cell

Question 13

what is the mitochondria? and its function?

Answer 13

the power plant of the cell

function- converts food energy into cellular energy (ATP)

Question 14

what is adenosine triphosphate (ATP)?

Answer 14

the chemical bond between the last two phosphate groups is broken, energy is released when terminal phosphate group is removed

Question 15

how do we use ATP?

Answer 15

• synthesis of new compounds (e.g. proteins)
• transport of molecules across membranes
• mechanical work (e.g. contraction of muscle cells)

Question 16

what are the functions of the plasma membrane?

Answer 16

• forms a mechanical barrier (separates ICF and ECF)
• selective permeability (determines which molecules can move between the ICF and ECF)
• electrochemical gradient (important for neural and muscle function)
• communication and cell signalling (receiving and interpreting messages from other cells)

Question 17

what is the structure of the plasma membrane? and features of the structures?

Answer 17

• is a lipid bilayer (2 layers of phospholipids) and has a head and two tails
• phosphate head is hydrophilic (loves water) and negatively charged
• the fatty-acid tails are hydrophobic (hates water) and uncharged

Question 18

why are membrane proteins important?

Answer 18

• transports molecules between the ICF and ECF
• cell communication
• attaching to the extracellular environment or to other cells
• enzymatic activity
• cell to cell recognition

Question 19

what are the three types of cell junctions (cells joining to each other)?

Answer 19

1. Desmosomes: join together two cells w/out touching, bound by glycoprotein filaments attached to thickened cytoplasm, prevents tearing of the tissue when stretched
2. Tight Junctions: membrane proteins from adjacent cells fuse together, prevents passage of molecules between adjoining cells
3. Gap Junctions: tunnels from one cell to another, transport of ions and small molecules between cells