lecture 8: cell structure Flashcards
1
Q
What are the 9 components of an eukaryotic cell?
A
- Nucleus
- Ribosomes
- Cytoskeleton
- Mitochondrion
- Chloroplast
- Lysosome
- Vacuole
- Endomembrane System
- Cell Wall
2
Q
What are the 3 functions of the nucleus?
A
- Information storage: house most of organism’s genome in chromosomes
- Information processing: regulate gene expression
- Ribosome assembly: done within nucleolus
3
Q
Nucleus structure?
A
- Nuclear envelope
- Chromosomes
- Nucleolus
- Nuclear matrix (cytoskeleton of nucleus)
4
Q
What is the nuclear envelope made of?
A
- Double membrane: each consists of a lipid bylayer
- Large pores (circle of proteins) that regulate entry/exit of molecules
5
Q
What is the nucleolus?
A
- Distinct region located in nucleus
2. Site of ribosomal RNA (rRNA) synthesis & ribosome assembly
6
Q
What is a ribosome’s function?
A
To carry out protein synthesis
7
Q
What are the 2 locations in which ribosomes carry out protein synthesis?
A
- Free: in cytosol
2. Bound: on the outside of rough endoplasmic reticulum (rER)
8
Q
Ribosomes structure?
A
- Particles made of ribosomal RNA + ribosomal protein
- Non-membranous (not strictly considered organelles)
- Separeated in a large and a smal subunit, both containing special RNA molecules and protein
9
Q
What is the cytoskeleton?
A
- Estensive network of protein fibers extending throughout cytoplasm
- Dynamic system, constantly remodeled
10
Q
What are the 2 functions of the cytoskeleton?
A
- Cell shape and support: gives distinctive shape + high level of internal organization (structure provides support & protection)
- Movement: intereact with motor proteins to move inside of cell + cell itself
11
Q
How do mivrovillus (microvilli) maintain their structure and shape?
A
With the help of the cytoskeleton (plasma membrane is too liquid to held them up)
12
Q
What are 3 examples of movement within the cell
(by cytoskeleton and motor proteins)?
A
- Chromosome movement during cell division
- Vesicle movement to transport cargo within the cell
- Flow of cytosol and organelles around plant cell
13
Q
What are 3 examples of movement of the cell
(by cytoskeleton and motor proteins)?
A
- Cilia: small hairs to move cell in a “swimming” matter
- Flagellum: small tail
- Amoeboid movement: like a “blob”, moving by changing cell shape
14
Q
What are the 2 organelles involved in energy transformation?
A
- Mitochondria (plants and animals)
2. Chloroplast (only plants)
15
Q
Mitochondria function?
A
- Sites of cellular respiration: Sugar +O2 —> CO2 + H2O + ATP (provide energy source)
16
Q
Mitochondria structure?
A
- Double membrane: smoother outer memebrane + inner membrane —> 2 compartments
- Fold of inner membrane = large surface area —> machinery for cellular respiration
17
Q
What is ATP?
A
Adenosine triphosphate: the energy currency in cells
- Energy is released when ATP is hydrolyzed (reacts with water)
18
Q
Chloroplasts function?
A
- Sites of photosynthesis: CO2 + H2O + Sunlight —> Sugar + O2
19
Q
Chloroplast structure?
A
- Member of a family of organelles called plastids (specialized in photosynthesis)
- Contain pigments + other enzymes and molecules that function in photosynthesis
- Double membrane + 3rd internal (thylakoid) membrane that forms internal network —> 3 compartments
- Machinery for photosynthesis = imbedded in thylakoid membrane
20
Q
4 common characteristics between mitochondria and chloroplasts?
A
- Double membrane
- Contain own DNA and protein synthesis machinery
- Are not part of endomembrane system: their proteins are made by free ribosomes or made by organelle’s own ribosomes
- Semiautonomous (own little factory, but not completely)
21
Q
What are the 2 elements of the endosymbiont theory?
A
- Mitochondria = result of ancient MUTUALISM between ancestor of eukaryotic cell & type or prokaryotic cell with ENERGY metabolsim that used O2
- Chloroplast = result of ancient MUTUALISM between early eukaryotic cell and a PHOTOSYNTHETIC prokaryotic cell giving rise to first photosynthetic eukaryotic cell
1 happened before 2, as plants cells have both mitochondrion and chloroplasts
22
Q
What are lysosomes’ 2 functions?
A
(in ANIMAL cells)
- Used for digestion of:
a) material from outside cell (taken in by endocytosis/phagocytosis)
b) worn-out cell structures (autophagy = self-eat; get ried of things they don’t need anymore) - Smaller components used for energy/ RECYCLED as building blocks
23
Q
Lysosome structure?
A
- Single-membrane-bound structures
- Contain acid + ≈40 different digestive enzymes (that break down molecules for digestion)
24
Q
What are vacuoles?
A
- Multifunctional compartments: storage, regulation of cell volume, degradation of wastes
- Single-membrane bound compartments
- Prominent in PLANT cells, fungal cells, some protists
25
What are 3 types of vacuoles?
1. Central vacuole: large, found in manye mature plant cells —> metbolically dead and do not need nutrients & do not produce wastes, so helps SA:V problem
2. Contractile vacuole: pump out excess water out of cells, then disappears
3. Food vacuoles: formed by phagocytosis (“food” from outside of cell” —> digestion like lysosomes
26
What are the 4 functions of a central vacuole in plants?
1. Stores water
2. Stores chemicals: ions, proteins (seeds), pigments (petals) ,toxins (against herbivores) —> depends of type of cell
3. Digestion and recycling (acts as lysosomes)
4. Exerts turgor pressure —> provides support and structure for plant and important for growth
27
Why doesn’t a plant cell burst under pressure?
Because of cell wall
28
Whar are the 4 main compartments of the cell?
1. Nucleus
2. Cytosol
3. Semiautonomous organelles
4. Endomembrane system
29
Endomembrane system functions?
- Makes proteins and lipids —> modifies, sorts, and transports htem to specific locations within cell or for secretion (released from cell by exocytosis)
30
What are the 2 ways the specialized organelles in the endomembrane system can transfer cargo from one to another?
1. Direct connection
| 2. Indirectly with transport vesicles
31
What are the main 3 components of the endomembrane system?
1. Smooth endoplasmic reticulum (sER)
2. Rough endoplasmic reticulum (rER)
- ER = more than half of total membrane of cell)
- ER is continuous with the intermembrane space of nuclear envelope
3. Golgi apparatus
32
Smooth ER structure?
- Membrane-bound tubes
| - NO ribosomes
33
Smooth ER 4 functions?
Contains enzymes invoveld in:
1. Metabolism of lipids
2. Storage/metabolism of carbohydrates (store energy)
3. Detoxification of poisons
4. Stores Ca 2+ (for muscle contraction)
34
Why is sER extensive in testes, liver cells and muscle cells?
1. Testes: hormones —> steroids which are lipids
2. Liver cells —> filter and get rid of toxins
3. Muscle cells —> Ca 2+ for muscle contraction
35
Rough ER structure?
- Membrane-bound sacs
| - Studded with ribosomes
36
Rough ER 2 functions?
1. Bound ribosomes synthesize proteins (for components of endomemebrane system OR secretion form cell)
2. Modifies proteins by adding carbohydrates —> forming glycoproteins
37
Golgi apparatus structure?
Series of stacked flat membranous sacs
38
Golgi apparatus 3 functions?
1. Receives lipids/proteins form ER via transport vesicles
2. Modifies these molecules via enzymes
3. Sorts, packages, and ships cargo to various destinations via transport vesicles
39
What is the secretory pathway?
- Accomplished by endomembrane system
- Proteins products (and protein hormones and enzymes) are produced, modified, sorted, and secreted outside of cell by exocytosis
40
Exocytosis vs Endocytosis
- Exo = bring things outside of cell
| - Endo = bring things inside of cell
41
What are extracellular components?
Materials that are external to the plasma membrane
42
What are the 3 functions of extracellular components?
1. Provide structural support and protection
2. Attach cells together to form tissues
3. Cell communication
43
What are 2 extracellular structures?
1. Cell walls in plant cells
| 2. Extracellular matrix (ECM) in animal cells
44
What are the 2 aspects of the structure of extracellular components?
1. “gel” that resists compression
| 2. “fibers” that resist tension
45
Plants’ cell wall 5 functions?
1. Maintains cell shape
2. Protects cell against: 1. mechanical stress (resist bursting) and 2. pathogens
3. Joins cells and organizes them into tissues
4. Provides support for plant
5. Allows cells to communicate (allows things out and in cells)
46
3 components of cell wall’s structure?
1. Primary cell wall (outside)
2. Secondary cell wall (on the inside): specialized depending on type of organism
3. Middle lamella: the “glue” that joins cells together
47
What makes up the primary cell wall?
1. Fibers = cellulose
| 2. Gel = pectin (like in jam) —> helps to solidify
48
What is present in plants cells, but not in animal cells? (3)
1. Cell wall
2. Chloroplast
3. Central vacuole (digests like lysosomes)
49
What is present in animal cells, but not in plant cells? (2)
1. Lysosomes
| 2. Centrosomes (cytoskeleton structure)
