Lecture 7

Question 1

Mitochondria

Answer 1

POWERHOUSE OF THE CELL
Sites of cellular respiration
Present in both plant and animal cells
Main producer of ATP (energy that cells require)

Question 2

Chloroplasts

Answer 2

Present in only plant cells
Site of photosynthesis:
Converts solar energy into chemical energy

Question 3

Similarities between Mitochondria and Chloroplasts

Answer 3

1. Both typically have two membranes surrounding them
2. Like prokaryotes, both contain ribosomes and circular DNA molecules
3. Both are semi-autonomous organelles that can grow and reproduce within the cell

Question 4

Cytoskeleton

Answer 4

A network of fibers, extending throughout the cytoplasm
Functions: Structural support (mechanical support and anchors internal cellular components) and Motility (movement within the cell and of cell from place to place)
Structural Elements: Microfilaments (MF), Microtubules (MT), Intermediate filaments (IF)

Question 5

Cytoskeletal Elements

Answer 5

Composed of subunits (polymers composed by monomers)
Polarized (MT and MF) so they display a + end and - end
Rapid assembly and disassembly (MF and MT)
IF are more stable

Question 6

Microfilaments (Actin Filaments)

Answer 6

Two intertwined strands of actin subunits (solid rods)
Smallest of the three
Polarized (subunits added to + end and subtracted from - end)
Dynamic (Rapid assembly and disassembly)
Function: Maintain cell shape, intracellular transport over short distances w/ myosin motor proteins, contraction of muscle

Question 7

Pseudopodia

Answer 7

Cellular extensions that allow a cell to crawl

Question 8

Intermediate Filaments

Answer 8

Middle size
Supercoiled into thick cables (so stable and resistant)
Function: Maintain cell shape and resist tension, maintain cell and nuclear anchorage, and makes up the nuclear lamina

Question 9

Lamin

Answer 9

IF that forms the nuclear lamina
Mutations to the lamina cause accelerated aging in humans (PROGERIA)
Lamin mutations lead to alterations in nuclear assembly and disassembly during cell division, abnormal nuclear architecture, and defective chromosome organization

Question 10

Microtubules

Answer 10

Made of tubulin dimer (molecule made up of two components) in hollow, cylindrical rods
Polarized
Function: Maintains cell shape and organizes cytoplasmic components, serves as a track for movement of cellular components
Grows out of centrosome - region that’s usually located near the nucleus
Centrioles - composed of 9 sets of triplet MTs in a ring
Some eukaryotic cells have flagella and cilia, which move fluid over the surface of tissue and contains MTs
Kinesins - move towards + end of MT
Dyneins - move towards - end

Question 11

Extracellular Matrix (ECM)

Answer 11

Made up of glycoproteins
Integrins (integrate ECM and Cytoskeleton) in membrane link ECM proteins like fibronectin with the cytoskeleton, facilitating crosstalk

Question 12

Peroxisomes

Answer 12

Membrane-bound organelle formed by proteins and lipids in the cytosol (not part of endomembrane system)
Function: breaks down fatty acids and detoxifies alcohol and other poisons

Question 13

Cellulose

Answer 13

polysaccharide used to synthesize cell walls for plants (cell walls only in plants)