Cell Structure and Organisation Flashcards
What are all living organisms composed of?
One or more cells
What are cells?
The basic unit of life
What is the cell the fundament unit of ?
Structure
Function
Organisation
-In all organisms
What is the cell theory?
Cells can only arise from pre existing cells
What are the organelles of a generalised ultrastructure of an animal cell?
Centrioles
Mitochondrion
Lysosome
Rough endoplasmic reticulum
Nucleus
Smooth endoplasmic reticulum
80S ribosomes
Cell membrane
Cytoplasm
Secretory/golgi vessel
Golgi apparatus
What are the features of the nucleus?
Nucleolus
Chromatin
Nuclear pore
Nuclear Envelope( 2 membranes)
What is an organelle?
a specialised structure inside a with specific functions
What are the organelles of a generalised ultrastructure of a plant cell?
-Plasmodesma
-middle lamella
-Vacuole
-SER
-Plasma membrane(pressed against cell wall)
Ribosomes
Ribosomes
Nucleus
RER
Chloroplast
Cytoplasm
Golgi apparatus
Golgi Vesicle
Mitochondrion
What does the vacuole consist of?
Tonoplast
Cell sap
What does the chloroplast consist of?
grana
envelope
What do the measurements measure?
Km-ecosystem
m- larger organisms
mm- tissues
um- cells and organelles
nm- molecules/viruses
What is the purpose of microscopy?
to magnify small objects such as biological specimens mounted on glass slides
What are the features of a light microscope?
Objective power lens(4,10,40,100x)
Stage clips
Stage
Diaphragm
Light source
Base
Eye piece
Arm
Fine and course focus
Adjuster to move stage
Power cord
What is the power of the eyepiece lens?
10x
What is the power of the low power objective lens?
x4 (total magnification x 40)
what is the power of the medium power objective lens?
x 10 (total magnification x100)
what is the power of the high power objective lens?
x40 (total magnification x400)
how do you calculate the total magnification of microscope lens?
eyepiece x objective
why must the sample be thin when preparing it to view under microscope?
To allow light to pass through
why must a sample be stained to be viewed under a microscope?
So structures can be seen clearly, and adds contrast
Why might staining be a disadvantage when preparing a sample to be viewed under a microscope?
Stain could be toxic/harm or killed the organism
What is the nucleus and what is its function?
-largest organelle in the cell
-function is to retain the genetic information (DNA) which codes for protein synthesis
what is the nucleus surrounded by?
A double membrane (nuclear envelope)
What is the nucleus made up of?
nuclear envelope
Nucleoplasm
Chromatin
Nucleolus
What is the nuclear envelope?
-A double membrane (outer and inner) with nuclear pores to allow the transport of mRNA and ribosomes out of the nucleus to the cytoplasm
what is nucleoplasm?
cytoplasm like material within the nucleus, which contains chromatin
What is chromatin and what does it do?
-Made up of coils of DNA, bound to histone protein.
-During cell division, the chromatin condenses to form the visible chromosomes
What is the nucleolus and what does it do?
-small, spherical body (one or more within the nucleus)
-They synthesise ribosomal RNA
-Site of ribosome production
what is the structure of mitochondria?
usually oval shape, bound by a double membrane with a narrow fulfilled intermembrane space
What is the function of the mitochondrion?
To release an energy in the form of ATP during aerobic respiration
what forms extensions called cristae?
-The inner membrane of the mitochondria is folded inwards
what does the cristae do?
The cristae increases the surface area for ATP to occur
Where is the matrix found?
Inside the mitochondrion
what is the organic matrix?
-contains many chemical compounds, including lipids, proteins, small (70S) ribosomes, and a small circle of DNA to allow self replication in response to the energy needs of the cell
-Where all chemical reactions take place
Where do the stages of aerobic respiration occur in the mitochondria?
In the matrix and on the inner membrane
Where are large numbers of mitochondria found
In the liver and muscle cells
How am mitochondria adapted to perform their function?
-largest surface area to volume ratio: increased gas exchange
-cylindrical: decreases distance for diffusion
-Folding of inner membrane/cristae- increased SA for enzymes/ more release of energy
What are ribosomes?
site of protein production
What are the small sub unit and large sub unit made of?
rRNA and protein
What occurs in the ribosomes?
Protein synthesis- mRNA from the nucleus fits into the groove between the 2 subunits and provides the code for a sequence of amino acids
Where are ribosomes found?
Free in the cytoplasm or associated with RER
What is the Rough Endoplasmic Reticulum?
an internal system of flattened membranous sacs, or cisternae, which are continuous with the nuclear membrane
What is the RER covered in?
Ribosomes
(gives it its name)
What the function of the RER?
protein synthesis and transport of proteins (polypeptide made by ribosomes), so it is present in large numbers in cells that synthesise large quantities of protein
What is the SER?
similar instructor to the RER has no ribosomes, hence its name
what is the SER involved in?
The synthesis and transport of lipids
What cells have extensive endoplasmic reticulum?
cells that store large quantities of carbohydrate, protein or fat (including liver and secretory cells)
what is the Golgi body made up of?
interconnected flattened membranous sacs
what fuses with the Golgi body?
Vesicles containing polypeptides pinch off from the RER and fuse with the gorge body
What happens when the verticals and the Golgi body fuse?
Hair proteins are modified and packaged into the vesicles, at the end of the Golgi body, Vesicles containing modified proteins bud off
What are the golgi’s main functions?
-Modifying and proteins (e.g. enzymes) into secretory vesicles for secretion from the cell
-producing glycol protein
-Forming lysosomes
what does the Golgi body also have a role in?
-transporting and storing lipids
-Secreting carbohydrates, e.g for formation of plant cell walls
what are lysosomes?
Single membrane, bound vesicles that contain hydrolytic (digestive) enzymes
What are lysosomes produced by and what do they do?
They are produced by the Golgi body and isolate, potentially harmful digestive enzymes from the remainder of the cell
what are the functions of lysosomes?
-They release, hydraulic enzymes when the cell needs to breakdown, worn out organelles
-they digest material that has been taken into the cell. For example, lysosomes fuse with the vesicle made when a white blood cell engulf bacteria by phagocytosis, and there enzyme digest the bacteria.
The synthesis and secretion of protein is from the cell—>
- The nucleus contains the DNA which is copied (during transcription) to produce MRNA.
2.Nuclear pores in the nuclear envelope allow mRNA molecules to
leave the nucleus and attach to ribosomes in the cytoplasm or on the RER. - Protein synthesis occurs on ribosomes (which are composed of rRNA and protein and synthesized in the nucleolus).
- Poly peptides are moved through the RER and are packaged into vesicles. The vesicles bud off the RER and carry the polypeptides to the Golgi body.
- The vesicle fuses with the membranes and shed its contents into the Golgi apparatus. Here the protein is modified.
6.At the other end of the Golgi body, vesicles containing the modified proteins bud off. - They may be secretory vesicles., which carry the proteins to the cell
membrane for secretion by exocytosis. Alternatively these may be
lysosomes containing digestive enzymes which will be used within the cell
What is the list of organelles involved in the synthesis and secretion of proteins from the cell in order?
nucleus
nuclear pore
ribosomes
RER
Golgi body
secretory vesicle
cell membrane
what are all cells surrounded by?
A cell surface membrane or plasma membrane
What are the principal biochemical components (cell membrane)?
phospholipid and protein molecules
how are the phospholipid molecules arranged in a cell membrane?
arranged as a bilayer, with one sheet of phospholipid opposite another
what is actual width of the cell membrane?
7-8 nm
What are the structural components of the membrane?
phospholipids
proteins
Carbohydrates
Cholesterol
what do phospholipids form?
bilayers with hydrophilic, heads, pointing outwards, interacting with the tissue fluid/blood plasma that surrounds the cell, and the cytoplasm in inside the cell
what is the structure of a phospholipid
-Phosphate group (polar head hydrophilic)
-Ester Bond
-Fatty acid (non polar, hydrophobic)
Why do the hydrophobic tails of both layers in the phospholipid point towards the inside of the membrane?
-The tails, repel water present in the side of plasm and extra cellular fluid, and the heads are attracted to this water
what do cell membranes appear as when viewed under the electron microscope?
As a double line
why does the dye used to stain cell membranes associate with the hydrophilic phospholipid heads?
it is a water soluble dye
(phospholipid heads appear dark)
What are all proteins in the membrane?
Globular
where on the cell membrane can proteins be found?
on the surface of the bilayer or partly embedded (extrinsic) or extending completely across both phospholipid layers (intrinsic/transmembrane)
describe and explain the position of the charged or hydrophilic parts of the protein in relation to the phospholipids—
-Charged parts of the protein are attracted to the phosphate heads
-uncharged parts of the protein associate with the nonpolar fatty acid tails of the phospholipids