Lecture 7

Question 1

What is an organelle?

Answer 1

1. Specialized structure within a cell that performs a specific function.
2. Membrane-enclosed: one or more cell membranes forms the boundary: see lecture 6
3. Contains fluid

Question 2

are ribosomes organelles

Answer 2

Ribosomes are not considered to be organelles: 1) no membrane or fluid 2) Continuously disassemble & reassemble.
Ribosomes are called complexes
Present in eukaryotes & prokaryotes

Question 3

The number of each organelle may differ depending on?

Answer 3

the cell type and

the activity of that cell

Question 4

Plant central vacuoles can take up to ..% cell volume

Answer 4

Can take up to 80% of cell volume (Huge !)

Question 5

plants central vacuole function

Answer 5

Water storage
Digestion
Store toxins or pigments
Can contain poisons/kill predators

Question 6

what are Chromoplasts

Answer 6

make & store pigments

Question 7

what are Amyloplasts

Answer 7

store starch

Question 8

what do Chloroplasts do

Answer 8

photosynthesis
Make & store sugar (as starch)

contain Chlorophyll (green): main pigment that traps light energy

Question 9

do all plant cells have chloroplasts

Answer 9

no, only the ones doing photosynthesis

Question 10

which organelle does cell. resp

Answer 10

mitochondria

transfer chemical energy in carbs, aa, fatty acids, into chemical energy in ATP

Question 11

what is the nucleus surrounded by

Answer 11

Surrounded by nuclear envelope: double cell membrane with nuclear pores (molecules enter & leave)

Nuclear pores allow for passage of materials into & out of the nucleus (ex RNA, ribosome subunits)

Question 12

function of nucleus

Answer 12

Protects & stores DNA
Almost all DNA (genetic information) is here
Small amount of DNA also found in the mitochondria

DNA replication & transcription (mRNA, rRNA & tRNA) takes place here

Influences cell structure & function
Genes on DNA determine which proteins get made
Proteins determine cell shape and function

Question 13

what are chromosomes made up of

Answer 13

dna + protein

Question 14

function of Nucleolus

Answer 14

Where proteins + rRNA put together to make a ribosomal subunit (which are then exported to cytoplasm)

Nucleolus is not enclosed by a membrane, not an organelle
(both animal and plant cells)

Question 15

ribosomes are complexes made up of?

Answer 15

Complex (not an organelle) made up of 2 different subunits

Each subunit contains:
rRNA
Proteins
that are need for translation to occur

Not surrounded by a membrane

Question 16

where are ribosomes located in the cell?

Answer 16

In Eukaryotes can be on the rER or free in cytoplasm.

In Prokaryotes: free in cytoplasm

Question 17

function of free ribosomes and the ones on the rER

Answer 17

Free ribosomes: proteins for the cytoplasm: ex cytoskeleton, enzymes in the nucleus…

Ribosomes on the rER:
enzymes to be packaged into lysosomes or
2) proteins to be secreted (ex hormones)
3) proteins that will be inserted into the plasma membrane (receptors, cell junctions, protein channels)

Question 18

diff between rough and smooth ER

Answer 18

Smooth:
No ribosomes
Makes lipids
Drug detoxification (fyi ex, morphine & some pesticides) Stores Ca2+

Rough:
Ribosomes on surface
Make proteins: ex transport proteins in plasma membrane

Question 19

functions of Golgi (apparatus)

Answer 19

1. Modifies proteins & lipids (ex attach a CHO, phosphates..)
2. Sorts: proteins made on the rER passes to the Golgi, which then directs the protein to other organelles or to the plasma membrane
3. Golgi is also part of the pathway that makes lysosomes

Question 20

what are Peroxisomes

Answer 20

membranous sacs containing enzymes used to detoxify substances such as alcohol, & free radicals. Also breaks down long fatty acids into shorter ones for the mitochondria to use

Question 21

function of Mitochondria

Answer 21

(Glucose) + ADP + P + O2 → ATP + CO2 + heat
Glucose, Fatty acids, Amino acids + Oxygen
give
ATP (40%) + CO2 + Heat (60%)

Question 22

Energy in food per gram

Answer 22

Carbohydrates: 4 kcal (4 Calories)
Proteins: 4 kcal (4 Calories)
Fats: 9 kcal (9 Calories)

Question 23

When you exercise:
Why do you breathe faster?
Why do you get hot? Why does your heart rate increase?

Answer 23

Why do you breathe faster? BRING IN MORE OXYGEN AND GET RID OF EXCESS CO2

Why does your heart rate increase? BRING YOUR GLUCOSE, FA (REACTANTS) TO THE CELLS. BLOOD SHOULD FLOW MORE IN THE LUNGS AND ACTIVE MUSCLES.

Why do you get hot? MAKE MORE ATP AND MORE HEAT (MORE CELLULAR RESPIRATION)

Question 24

true or false? plants do both photosynthesis and cellular respiration

Answer 24

true.

Question 25

function of lysosomes

Answer 25

break down excess or worn-out cell parts. They may be used to destroy invading viruses and bacteria.

Question 26

do plant cells have lysosomes

Answer 26

no.

Question 27

what is the cause of the Tay-Sach’s disease

Answer 27

Missing an enzyme (Hex-A) in lysosomes

Can’t break down lipids in nerve cells

Question 28

what are Centrioles and what is their function

Answer 28

Composed mainly of a protein (called tubulin)
Not an organelle

The main function of centriole is to help with cell division in animal cells

Question 29

do plant cells have centrioles

Answer 29

no.

Question 30

…, …, and … are present in cell membranes.

Answer 30

proteins (including glycoproteins), cholesterol, and carbohydrates are present in cell membranes.

Question 31

functions of the cell membrane proteins

Answer 31

form channels or are carriers/pumps; are hormone or neurotransmitter receptors; can be enzymes; some are molecules involved in cell recognition, others hold one cell to another, allowing the formation of tissues.

Question 32

what does it mean that the plasma membrane is selectively permeable

Answer 32

Selectively permeable means a membrane allows the passage of some molecules or ions and inhibits the passage of others.

Question 33

why lipid-soluble molecules can pass more easily than non-lipid soluble molecules

Answer 33

Because of the chemical and structural nature of the phospholipid bilayer (hydrophobic core), only lipid-soluble molecules and some small molecules are able to freely pass through the lipid bilayer.

Question 34

what molecules can pass through the plasma membrane

Answer 34

Only the smallest molecules like water, carbon dioxide, and oxygen can freely diffuse across cell membranes.