Cell Organelles Flashcards
1
Q
Cell Theory
A
all organisms are made up of cells, which are the basic fundamental unit of life and arise from pre-existing cells
2
Q
Cell Membrane
A
- semi-permeable outer boundary of the cell that separates the cell from neighbouring cells and from the external environment
- made up of a double layer of lipid molecules and associated proteins
- exposed heads of the bilayer are hydrophilic however the tails are hydrophobic so that the cell membrane acts as a protective barrier to the uncontrolled flow of H2O
- determines the movement of substances into and out of the cell
3
Q
Cytoplasm
A
- the thick-fluid (cytosol) within the cell membrane and contains all the cell organelles excluding the nucleus
- all the functions required for growth and replication take place in the cytoplasm
- it provides a medium for the transport of materials the cell uses and produces
- it provides support for the organelles and inclusions of the cell as the cytosol suspends them
- helps maintain the shape of the cell
- acts as a site for the essential metabolic reactions
4
Q
Cytosol
A
- the liquid part of the cytoplasm
- 75-90% water with a complex mixture of dissolved substances (salts & carbohydrates) and undissolved substances (proteins and fats)
- it plays a major role in controlling the osmotic pressure of the cell and the flow of chemicals in and out of the cell
- it is where metabolic reactions occur
5
Q
Nucleus
A
- largest organelle and is usually spherical and oval in shape
- nuclear membrane (which is a double membrane) separates it from the cytoplasm
- numerous gaps in the membrane, called nuclear pores, allow large molecules such as messenger RNA to pass through the pores to the ribosomes, while DNA is prevented from leaving
- communicates with surrounding cytosol via the nuclear pores
- controls the protein production and function of other parts of the cell
6
Q
Nucleolus
A
- it is responsible for producing ribosomes which move out of the nucleus and take position on the rough ER
- composed mainly of RNA
- DNA and nucleolus are suspended in a jelly-like nucleoplasm
7
Q
Ribosomes
A
- small, spherical with two subunits (large summit and small summit)
- may be free in the cytoplasm or attached to membranes within the cell such as ER
- amino acids are joined together to make proteins (protein synthesis)
8
Q
Endoplasmic reticulum
A
- pairs of parallel membranes extending through the cytoplasm and connecting the cell membrane with the nuclear membrane
- provides a surface on which chemical reactions can occur
- the channels between the paired membranes are used for the storage or transport of materials
- rough ER: has ribosomes to attached, transports substances with the cytoplasm, protein synthesis occurs on the ribosomes
- smooth ER: transports substances within the cytoplasm, no ribosomes
9
Q
Golgi
A
- flattened membranes stacked on top of each other
- it modifies and sorts proteins produced in the ER and packages them for secretion from the cell
- proteins produced at the ribosomes pass through the channels of the ER to the Golgi apparatus
- at the edged of the membranes of the Golgi body, small sacs of liquid containing proteins are formed
- these sacs are surrounded by a membrane and are called vesicles
- if the Golgi complex makes a mistake in shipping the proteins to the right address certain functions in the cell stop
10
Q
Vesicle
A
- a membrane-bound sac that helps store ad transport materials into and out of the cell
- some deliver materials to parts of the cell and others transport materials outside the cell in a process called exocytosis
- smaller than a vacuole
11
Q
Lysosomes
A
- small spheres bound by a membrane
- formed from the golgi body
- contains enzymes able to break down large molecules (proteins, lipids, nucleic acids, some carbohydrates)
- they break down materials taken into the cell or break down worn-out organelles
12
Q
Mitochondria
A
- spherical or elongated structures through the cytoplasm
- has a double membrane
- smooth outer membrane surrounds and encloses the entire structure
- inner membrane, is arranged into a series of folds called cristae, that extend into the interior of the organelle
- between the membranes is the intermembrane space - site for cellular (aerobic) respiration where chemical potential energy of food molecules is converted to ATP (energy currency)
- foldings of the inner membrane create a large SA on which cellular respiration can take place
13
Q
Cilia and flagella
A
- fin projections that can beat back and forth to move either the whole cell or substances over the surface of the cell (e.g. mucus with trapped debris and dust)
- is projections are short and numerous, resembling hairs, they are called cilia
- e.g. cilia in the cells lining the trachea move mucus and trapped particles away from the lungs
- is they are longer and there is only one or two they are called flagella
- e.g flagella in sperm cells help them swim
14
Q
Cytoskeleton
A
- framework of protein fibres that gives the cell its shape and assists cell movement
- consists of:
- microtubules: hollow rods that keep organelles in
place or move them around the cell, helps maintain
shape of the cell - microfilaments: protein fibres which move materials
around the cytoplasm or move the whole cell - intermediate fibres
- microtubules: hollow rods that keep organelles in
15
Q
Centrioles
A
- a pair of cylindrical structures usually located near the nucleus
- spindle fibres originate from the centrioles
- involved in the reproduction of the cell (cell division)
