eukaryotic cell ultrastructure Flashcards
(32 cards)
1
Q
what does the cell theory state
A
- cells are the basic unit of life
- all organisms are made up of cells
- cells arise from pre-existing cells by division
- cells contain information (DNA) used as instructions for growth, development and functioning
- chemical reaction to mantain life takes place inside cells
2
Q
size comparison of cells + organelles
A
plant cell > animal cell > nucleus > chloroplast > mitochondria > lysozome > ribosome
3
Q
major structural features of eukaryotic cells
A
- cell surface membrane
- nucleus
-
cytoplasm contains:
* cytosol (fluid)
* organelles
* cytoskeleton (support and mantain shape of cell)
4
Q
structure of the nucleus
A
- double membrane
- has nuclear pores
- contains DNA
- contains one or more nucleolus
5
Q
functions of the nucleus
A
- controls cell activity by regulating protein and enzyme synthesis
- nuclear division is the basis of cell replication
- nucleolus synthesises and partially assembles ribosomes
- synthesises DNA
6
Q
structure of cell surface membrane
A
- phospholipid bilayer with hydrophobic tails on interior and hydrophillic heads on exterior
- phospholipid consists of a phosphate group attached to two fatty acid chains
7
Q
function of cell surface membrane
A
- partially permeable membrane
- barrier between cytoplasm and environment
- prevents most water soluble subtances from entering or leaving cell
8
Q
structures of centrioles
A
- cylindrical structures composed of microtubules
- two centrioles make a centrosome
- found in pairs in only animal cells or single structures
9
Q
functions of centriole
A
- produces spindle fibers which attach to and seperate chromosomes during cell division
- forms cillia and flagella
10
Q
structure of ribosomes
A
- no membranes
- made out of protein and RNA
- 2 subunits - large and small
- found attached to the RER or freely in cytosol
11
Q
function of ribosome
A
site of protein synthesis
12
Q
structure of endoplasmic reticulum
A
- found on outer nuclear envelope membrane
- consists of a network of membranous sacs called cisternae
- smooth ER has no ribosomes, rough ER has ribosomes on its surface
13
Q
functions of ER (smooth and rough)
A
SMOOTH ER:
synthethises lipids and steroid hormones
ROUGH ER:
site of protein synthesis and transport through cisternae
14
Q
structure of golgi apparatus
A
- consists of FLATTENED membranous sacs called cisternae
- continually being formed at cis face and continually budded off at trans face where vesicles are pinched off
15
Q
function of golgi apparatus
A
- chemically modifies, sorts and transports molecules
- forms lysozomes
16
Q
structure of lysozome
A
- small spherical vesicles containing hydrolytic digestive enzymes
- single membrane
17
Q
function of a lysozome
A
- digestion of materials taken in by cell
- autophagy - digestion of worn out or improperly functioning organelles
- autolysis - self digestion of cell by releasing lysozome contents
18
Q
structure of mitochondria
A
- double membrane
- outer membrane : smooth and continuous
- inner membrane : extesively folded to form cristae that project into the interior (matrix)
- contains circular DNA, RNA, ribosomes
19
Q
function of mitochondria
A
releases energy via cellular respiration
20
Q
structure of chloroplast
A
- double membrane
- outer membrane : smooth and continuous
- inner membrane : gives rise to membranes named thykaloids which extends throughout the interior
- interior has a gel like matrix called stroma
- within the stroma, thykaloids are stacked into grana and joined by the intergranal lamellae
- green, contains photosynthetic pigments
- contains DNA
21
Q
function of chloroplast
A
site of photosynthesis
22
Q
structure of a vacuole
A
- fluid filled bound by a single membrane
- known as vesicles in animal cells
-
large central vacuole for plant cells,
surrounded by a membrane (tonoplast) containing cell sap
23
Q
functions of vacuole
A
- entry of water is important in cell expansion and normal water relations of plants
- hydrolytic enzymes sometimes present, can act as a lysozome
- waste products accumulate within vacuole
- some dissolved substances act as food reserves
24
Q
structure of cell wall
A
- plant cells - made out of cellulose
- strong yet permeable to let free passage of substances in and out of cell
for PROKARYOTES :
fungi – chitin cell wall
bacteria – peptidoglycan cell wall
25
function of cell wall
* **mechanical support**
* **protective layer**
26
organelle(s) with no membrane
**ribosome**
27
organelle(s) with single membrane
* **lysozome**
* **vacuole**
28
organelle(s) with double membrane
* **nucleus**
* **mitochondria**
* **chloroplast**
29
organelle(s) containing DNA
* **nucleus**
* **mitochondria**
* **chloroplast**
30
organelle(s) containing RNA
* **mitochondria**
* **ribosome**
31
differences between animal and plant cells
1. **cell wall**
animal : absent
plant : present, cellulose
2. **lysozome**
animal : present
plant : absent
3. **vacuole**
animal : small and scattered (vesicles)
plant : large and central
4. **centrioles**
animal : present
plant : absent
5. **choroplasts**
animal : absent
plant : present
32
describe the protein secretary pathway
1. **ribosome** bound to **RER** **synthesises polypeptide chains** into the **RER**
2. **protein** is enclosed in an **ER vesicle**. ER vesicle containing the protein **buds off from the RER**
3. **travels and fuses** with **cis face of GA**
4. GA **chemically modifies, sorts and transports the proteins.** The proteins move through the GA by **Golgi vesicles budding off from one cisterna** and **fusing with another.**
5. **secretory vesicle containing protein** **buds off trans face of the GA** , **travels and fuses** with **cell membrane**, hence **releasing protein out of the cell.**
