Cell: Unit of Life Flashcards
Nucleus: discovered by
Robert Brown
Nucleus: functions
- carrying genetic information from one cell generation to the next
- controls all metabolic activies of the cell by controlling the synthesis of enzymes
Chromosomes: discovered by
Strasburger
Chromosomes: term coined by
Waldeyer
Centromere
Primary constriction seen on a chromosome
Karyotype
The group of characteristics that identifies a particular chromosome set
Mitochondria: discovered by
Kolliker
Why are mitochondria called the powerhouse of the cell?
- Their primary function is the conversion and transfer of cellular energy
- They have the capacity of converting the potential energy of various food materials into the form of energy that can be used by cells to carry out various activities
Plastids (classify based on colour)
- Chloroplasts- green
- Leucoplasts- colourless
- Chromoplasts- coloured
Leucoplasts- functions
function as storage organelles and
store starch- amyloplasts
store oil- elaioplasts
store proteins- aleuroplasts
Chromoplasts
Plastids that mainly store carotenoids are called chromoplasts. They are found in flowers and fruits.
Chloroplasts- function
- Contain the green pigment chlorophyll which helps in the production of chemical energy by the process of photosynthesis.
- Contain quantosomes on the inner surface of the lamellar membrane which absorb a mole quantum of light
Structural and functional unit of chloroplasts
Quantosomes
Endomembrane structures
4 structures are collectively called the endomembrane structures because they form the endoskeleton of the cell:
1. Endoplasmic reticulum
2. Golgi apparatus
3. Lysosomes
4. Vacuoles
Two types of endoplasmic reticulum
- Rough endoplasmic reticulum-
- protein synthesis and transport
- ribosomes lie on the outer border of its membrane - Smooth endoplasmic reticulum-
- synthesis of glycolipids
- devoid of ribosomes
Golgi complex: discovered by
Camillo Golgi
Golgi complex: function
- Secretion
- Formation of lysosomes
Lysosomes were discovered by
Christian de Duve
Why are lysosomes called the suicide bags of the cell?
Lysosomes contain powerful enzymes that digest the cell contents along with the foreign substance
Lysosomes: functions
- Intracellular digestion
- Destruction of certain structures during the process of development
Membrane surrounding a vacuole
Tonoplast
Two types of vacuoles
Contractile: contract and release the extra fluid and salt from the cell
Food vacuoles: reserve food material
List the microbodies and their functions
- Glyoxysomes: main function is to convert fatty acids to acetyl CoA
- Peroxisomes: They contain the enzyme catalase which helps in the breakdown of the highly toxic H₂O₂ into water and oxygen
H₂O₂ —-catalase—-> H₂O + [O] - Spherosomes: storage and transport of lipids
Ribosomes: discovered by
Palade
Location of ribosomes
- mainly seen on the surface of rough ER
- also seen scattered in the cytoplasm
Svedberg Unit
Stands for the sedimentation coefficient
Ribosomes seen in eukaryotes
70s ribosomes
Ribosomes seen in prokaryotes
80s ribosomes
Ribosomes: functions
protein synthesis
Polyribosomes/polysomes
Ribosomes seen in clusters are called polyribosomes
Centrioles: composition
A centriole is made up of nine triplets of microtubules composed of tubulin protein
Centriole: function
Help in cell division
Centriole: location
Seen on either side of the spindle fibres
Tight junctions
In cell membranes, seal gaps between epithelial cells
Gap junctions
In cell membranes, allow the passage of small water molecules from cell to cell
Adherens junction
Connect actin filament bundles in one cell with that of the other cell
Glycocalyx
An animal cell does not have a cell wall, instead it has a cell coat made of short carbohydrate chains. This cell coat is called glycocalyx
Desmosomes
Thickened regions of the plasma membrane which permit intracellular electrical communication of inorganic ions
Facilitated diffusion
the process of spontaneous passive transport of molecules or ions
across a biological membrane
via specific trans-membrane integral proteins
like carrier proteins or channel proteins
Uniport transfer
Uniport transfer is when one ion or molecule crosses the protoplasmic membrane at one site
Example: Transfer of glucose molecule into the cell.
Symport transfer
Symport transfer is when two ions or molecules cross the protoplasmic membrane at the same time in the same direction
Example: Entry of glucose and Na molecule into the cell in the same direction
Antiport transfer
Antiport transfer is when two ions or molecules cross the protoplasmic membrane at the same time in the opposite direction.
Example: Transport of Na and K molecules across the membrane in opposite directions
