Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
44 Cards in this Set
- Front
- Back
|
Define Organelle
|
Functionally and distinct part of a cell
|
|
|
Define Compartmentilisation
|
Organelles themselves are surrounded by membranes so that their activities can be separated from the surrounding cytoplasm
|
|
|
Define Division of Labor
|
Sharing of work between different specialized organelles
|
|
|
Describe the features of a Nucleus
|
Largest Organelle between 10 to 20 µm in diameter
Enclosed be an nuclear envelope of 2 membranes perforated by nuclear pores Outer membrane continuous with ER Contains Chromatin and Nucleolus |
|
|
What is the function of a nucleus?
|
Chromosomes contain DNA
DNA is organised into genes which control all the activities of the cell The nucleolus manufactures ribosomes |
|
|
Describe the features of Rough ER
|
System of flattered, membrane-bound sacks called cisternae, forming tubes and sheets with ribosomes found on the surface
Continuous with the outer membrane of the nuclear envelope |
|
|
What is the function of Rough ER
|
Transport proteins are made by the ribosomes through the cisternae
|
|
|
Describe the features of Smooth ER
|
System of flattered, membrane-bound sacks called cisternae, forming tubes and sheets
No ribosomes found on the surface |
|
|
what is the function of a smooth ER?
|
Site of lipid and steroid synthesis
|
|
|
Describe the features of a Ribosome
|
Very small organelles (20nm)
Consist of a large and small subunit Made of roughly equal parts of protein and rRNA Slightly smaller ribosomes are found in mitochondria and chloroplasts |
|
|
What is the function of a Ribosome?
|
Site of protein synthesis
Either bound to ER or lie free in the cytoplasm May form polysomes (polyribosomes) |
|
|
Describe the features of a Mitochondria
|
rod shaped, 1 to 10µm in diameter
Surrounded by an envelope of 2 membranes Inner membrane folded to form Cristae Contains a matrix with a few ribosomes, a circular DNA molecule and phosphate granules |
|
|
What is the function of a Mitochondria?
|
In aerobic respiration, cristae is a site of oxidative phosphorylation and electron transport
Matrix is a part of Kreb's cycle Production of ATP |
|
|
Describe the features of a Golgi Apparatus
|
Stack of flattered membrane-bound sacs called cisternae, continuously formed at one end and budded off at the other end as vesicles
|
|
|
What is the function of a Golgi Apparatus?
|
Internal processing and transport system
Golgi vesicles transport the materials to the other part of the cell or to the cell surface membrane for secretion Makes Lysosomes |
|
|
Describe the features of a Lysosome
|
Up to 1µm in diameter
Simple spherical sac bounded by a single membrane and containing digestive (hydrolytic) enzymes No internal structures visible |
|
|
What is the function of a Lysosome?
|
Concerned with the breakdown of structures or molecules
e.g. get rid of old organelles and digest bacteria |
|
|
Describe the features of a Cell (Plasma) Membrane
|
About 7nm in thickness
Trilaminar appearance |
|
|
What is the function of a Cell (Plasma) Membrane
|
A partially permeable membrane controlling the import and export of selected chemicals between the cell and its environment
|
|
|
Describe the features of a Cell Wall
|
A rigid wall surrounding the cell, consisting of cellulose, microfibrils and ma be secondarily thickened in some cells
|
|
|
What is the function of a Cell Wall?
|
Provides mechanical support and protection
Allows a pressure to be developed which aids in support Prevents Osmotic bursting of the cell Pathway movement of water and mineral salts Freely permeable |
|
|
What is a Middle Lamina?
|
Thin layer of pectic substances
|
|
|
What is the function of a middle lamina?
|
cements neighboring cells together
|
|
|
What is a plasmodesma?
|
A fine cytoplasmic thread linking the cytoplasm of 2 neighboring cells through a fine pore in the cell walls, the pore is lined with the cell surface membrane
|
|
|
What is the function of a plasmodesma?
|
Enables a continuous system of cytoplasm, the symplast, to be formed between neighboring cells for transport of substances between cells
|
|
|
Describe the features of a Chloroplast
|
Biconvex disc, 2-10µm thick
Large plastid containing chlorophyll and carries out photosynthesis Surrounded be an envelope ot 2 membranes and contains a gel-like stroma through which runs a system of membranes that are stacked in places to form grana. May store starch Stroma also contains ribosomes, circular DNA molecule and lipid droplets |
|
|
What is the function of a chloroplast?
|
The organelle in which photosynthesis takes pace, light energy is converted to chemical energy
|
|
|
Describe the features of a Large Central Vacuole
|
A sac bounded by a single membrane called the tonoplast
Contains cell sap, a concentrated solution of various substances, such as mineral salts, sugar, pigments, organic acid and enzymes Typically large in mature cells |
|
|
What is the function of a Large Central Vacuole
|
Storage of various substances including waste products
Makes an important contribution to the osmotic properties of the cell Sometimes it functions as a Lysosome |
|
|
What are the features of a Centriole
|
Small hallow cylinder about 0.4µm long and 0.2µm in diameter that occur in pairs inmost animal cells
Formed by a ring of microtubulus "Triplets of nine" arrangement |
|
|
What is the function of a Centriole?
|
These Microtubules are used to grow the spindle fibers for nuclear division
|
|
|
What are Basal bodies, cilia and flagella?
|
Long, thin extensions that can move in a wale like manner
Long and few: Flagella Many and short: Cilia Usually 3-4µm long, 0.2µm in diameter Covered with an extension of the plasma membrane and it contains microtubules that extend throughout its length |
|
|
What are the functions of a Basal bodies, cilia and flagella?
|
To move substances around the cell or to move the cell itself as the cilia beat
|
|
|
Define magnification
|
The number of times larger, when image is compared with the real size of the object
|
|
|
what is the formula for magnification?
|
Size of image/Actual size of specimen
|
|
|
Define Resolution
|
The ability to distinguish between 2 separate points
|
|
|
What is the Maximum resolution of a light microscope?
|
200nm
|
|
|
What is the Maximum resolution of a electron microscope?
|
0.5nm
|
|
|
What are the 2 reasons for using electrons in electron microscope?
|
Their wavelength is extremely short
They are Negatively charged, therefore they can be focused easily using electromagnets |
|
|
what are the 2 types of electron microscopes?
|
Transmission electron microscope (TEM)
Scanning electron microscope (SEM) |
|
|
What are the Difficulties in using an electron microscope?
|
The specimen ad the florescent screen must be seen in vacuum
All specimen must be dehydrated because water boils at room temperature in vacuum |
|
|
What is the difference between a prokaryotic cell and a eukaryotic cell?
|
Eukaryotic cells are larger and the contain a nucleus
Prokaryotic cells are smaller and their DNA lies freely in the cytoplasm |
|
|
What are the Features in Prokaryotic cells?
|
Size: Smaller cells, about 0.5 - 5µm
DNA: Circular, lies free in cytoplasm Naked DNA May contain Plasmid Ribosomes: smaller, 18nm ER: None Cell Organelles: very few organelles 2-membrane organelles absent Cell wall: always present |
|
|
What are the Features in Eukaryotic cells?
|
Size: bigger, about 40µm
DNA: not circular and its inside the nucleus associated with protein Ribosomes: larger, 22nm ER: present Cell Organelles: Many cell organelles No membrane(ribosomes) Single membrane(lysosome, Ga, Vacuoles) 2-membraned(nucleus, mitochondria, chloroplasts) Cell wall: sometimes present(plant cell) |
