Cell (III) Organelles Flashcards
(37 cards)
Explain in Biological terms, what the term “organelle” means?
An organelle is a discrete structure within a cell, having a specific function.
Name all the organelles in both animal and plant cell.
Endoplasmic Reticulum (SER/RER) Golgi Apparatus Mitochondria Microtubules Cell wall vacuole Ribosomes Lysosomes Centrioles
What are the 2 types of Endoplasmic Reticulum?
Smooth Endoplasmic Reticulum (SER)
Rough Endoplasmic Reticulum (RER)
Describe the structure of the Endoplasmic Reticulum.
1) It is a network of folded membranes formed into sheets, tubes/sacs that are extensively interconnected.
2) (RER) has ribosomes attached to the outer surface.
3) SER has no ribosomes, more tubular.
What are vesicles?
Vesicles are small, spherical organelle bounded by a single membrane.
Mention one fact about the Endoplasmic Reticulum.
The cytoplasm of metabolically active cells is commonly packed with ER.
Explain the function of the ER.
1) RER is the site of synthesis of proteins that are ‘packaged in the vesicles. Transport proteins made by the ribosome to Golgi Apparatus for secretion.
2) SER is the site of synthesis of substances needed by a cell. It is important in the manufacture of lipids and steroids, and the reproductive hormones oestrogen and testosterone.
Describe the structure of the Golgi Apparatus/ Golgi body/ Golgi complex?
1) It consists of a stack-like collection of flattened membranous sacs.
Explain the function of the Golgi Apparatus.
Modify substances made by the endoplasmic reticulum. They store and package these substances in vesicles for secretion out of the cell.
Describe the structures of the Mitochondria?
- Metabolically, very active cells will contain thousands of them in their cytoplasm.
1) Appears mostly as rod-shaped or cylindrical organelles in electron micrographs.
2) Has a double membrane. Outer membrane is a smooth boundary, inner is infolded to form cristae.
3) It’s matrix (interior of mitochondrion) contains aqueous solution of metabolites and enzymes, and also small circular lengths of DNA.
Explain the functions of the mitochondria?
1) Site where aerobic stages of respiration takes place.
2) Site where synthesis of much ATP. Food is oxidised in aerobic respiration to release energy for cell activities e.g. cell division, growth.
Describe the structure of the ribosomes?
Ribosomes are minute structures, approx 25nm in diameter.
It is built of 2 sub-units, and do not have membranes as part of their structures.
It consist of proteins and a nucleic acid known as RNA.
Explain the function of ribosomes in a cell.
1) It is the site where proteins are made in a cell. Some of the cell proteins produced have structural roles for instance, collagen.
2) Collagens are biological catalysts -> They cause the reactions of metabolism to occur quickly under the conditions found within the cytoplasm.
Describe the structure of lysosomes.
1) They are tiny spherical vesicles bound by a single membrane.
2) They contain a concentrated mixture of ‘digestive’ enzymes. (hydrolytic enzymes), produced in Golgi Apparatus or by RER.
Explain the functions of lysosomes.
1) Breakdown of the content of ‘food’ vacuoles.
2) Foreign matter/ food particles taken up into these lysosomes are being broken down. [occurs when lysosome fuse with vacuole]
3) When organelle’s die, the hydrolytic enzymes in lysosomes of cells escape into the cytoplasm and cause self-digestion, known as autolysis.
Explain what autolysis is.
The destruction of cells or tissues by their own enzymes, especially those released by lysosomes.
Describe the structure of centrioles and microtubules.
Tiny organelle consisting on 9 paired of microtubules arranged in short, hollow cylinder.
Animal cells:
- Centrosome are formed when 2 centrioles occur at right angles, just outside the nucleus.
- Straight, unbranched hollow cylinders, only 25nm wide.
- Made of globular protein called tubulin. This is first built up and then later broken down in the cells as the microtubule frame work is required in different places for different tasks.
Function of centrioles and microtubules.
Centrioles:
-Absent in plant cell, they are a small body close to the nucleus that plays a part in cell division.
Microtubules:
-whether plants/ animals, the microtubules are well-organized, which shape and support the cytoplasm.
-Involved in movements of cell components withing the cytoplasm, too, acting to guide and direct organelles.
Which organelle helps shape and support the cytoplasm?
microtubules.
Which organelle is involved in movement of cell components within cytoplasm?
Microtubules. They are involved in movements of cell components within the cytoplasm, acting to guide and direct organelles.
Describe the structure of the chloroplast.
1) Large organelle, biconvex shape.
2) Occur in green plast, where most in the mesophyll cells of leaves.
3) The process that occurs in chloroplast is photosynthesis.
4) Has double membrane:
Outer layer-> continuous boundary.
Inner Layer: In-tucked to form a system of branch8ing membranes called lamellae/ thylakoids.
Which organelle is responsible for the process photosynthesis?
Chloroplast. It contains chlorophyll, which traps light energy for photosynthesis.
Describe the structure of vacuole in cells.
In animal: small and numerous and temporary.
In plants:
-One large and in the centre of the cell.
- contains cell sap, which is essentially salts and sugar dissolved in water.
-surrounded by a thin membrane called tonoplast, which functions just like the plasma membrane.
Explain the function of the vacuole in cells.
1) Store substances in cells such as food and water.
2) Contains cell sap which takes in water and keeps the cell turgid (firm)
