BABS1201 Lecture Notes - Lecture 3: Endoplasmic Reticulum, Nuclear Membrane, Aqueous Humour
4 May 2018
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1
Properties of water:
- Cohesion
- Adhesion
- Surface tension
- Low density
- High specific heat
- Universal solvent
Differences between prokaryotes and eukaryotes:
- Prokaryotes have no defined nucleus, DNA is in direct contact with cytoplasm
o No membrane bound organelles, no mitochondria
o Divide by binary fission, reproduce by meiosis through chromosome replication
o Smaller in size
o Contain DNA in the form of a single chromosome in a nucleoid
- Eukaryotes have a membrane bound nucleus separated from the cytoplasm
o Made from one or more cells
- Both have a plasma membrane, DNA in the form of chromosomes and ribosomes
Parts of an Eukaryote cells:
Cytoplasm
- Region between the membrane and the nucleus
- Contains the organelles of the cell
- Cytosol is the aqueous fluid that fills the cytoplasm
Nucleus – where
DNA directs RNA
synthesis
- Chromosome – 1 DNA molecule and associated proteins
- Chromatin – total collection of all DNA and proteins
- Nucleolus – site of RNA transcription
- Nuclear pores – passages where RNA and ribosomes pass out
of the nucleus and nuclear proteins pass in
Nuclear envelope
- Ribosomes attached to the surface
- Membrane is constant with the rough endoplasmic reticulum
Ribosomes – protein
factory, convert
DNA into RNA
- Non membrane bound structures
- Molecular machines that convert DNA carried by messenger
RNA into proteins
- Coordinates protein synthesis
Endoplasmic
reticulum
- Continuous with the outer membrane of the nuclear envelope
- Rough ER – coated with ribosomes, protein synthesis
- Smooth ER – no ribosomes, lipid synthesis
Transport vesicles
- Membrane bound sac
- Packages proteins for transport to the Golgi body
Golgi apparatus
- Sorts, modifies and packages proteins from the ER
Lysosomes
- Enzymes that breakdown lipids, carbs and proteins into small
molecules
Membrane
- Structure separating the inside and outside of the cell
- Controls traffic of materials
Mitochondria
- Membrane enclosed organelle
- Generates most of the cell’s ATP supply
Chloroplast
- Organelle found in plant cells, algae and some bacteria
- Absorbs light and use in conjunction with water and CO2 to
produce sugars
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2
What is a cell?
- Always enclosed by a membrane – selective barrier that controls movement
- All have a cytoplasm – aqueous part is the cytosol, suspends everything in the cells for
processes to occur
- All contain DNA – genetic material
- All have ribosomes – mechanism for protein manufacture
Cell theory:
- All life forms are made from one or more cells
- Cells only arise from pre-existing cells
- Cell is the smallest form of life
Genes:
- All cells use the same genetic code (GATC)
- Central dogma of molecular biology
o All cells replicate their DNA and produce proteins by transcribing DNA to RNA and
RNA into proteins
▪ DNA unravels to become RNA code goes to a ribosome to make a protein
▪ DNA transcription translation into a protein
Macromolecules:
- Large organic molecules formed by joining monomers (strong covalent bonds between
them) in a condensation or dehydration reaction to form polymers
- Macromolecules can be classed as: carbohydrates, lipids, proteins (amino acids, peptide
bonds and enzymes) and nucleic acids
- Carbohydrate monomers are monosaccharides, lipids are fatty acids, proteins are amino
acids and nucleic acids are nucleotides
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3
Group of
substances
Elements
present
Basic unit
Function in cells
Carbohydrates
C, H, O
Monosaccharides:
- Glucose (C6H12O6)
- Cellulose
- Fructose
Disaccharides:
- Sucrose
- Lactose
Polysaccharides:
- Starch
- Carbs, in particular glucose
provides energy for cells
- Mitochondria use oxygen and
sugars to make ATP
- In plants, starch is used to
storage and cellulose is used
for the cell walls
- Animals store glycogen as
granules for energy
Lipids
C, H, O
- Fatty acids
- Glycerol
- Steroids
- Lipids include fats, waxes,
steroids or oils
- Fats and oils store energy
- Waxes are used by plants in
the cell membrane for
evaporation
- Make up parts of hormones
Proteins
C, H, O,
N
- Polypeptides (chains
of amino acids)
- 20 different amino
acids
- Used to make and repair
cells, protein synthesis
- Regulate movements of
substances in and out of cells
Nucleic acids
C, H, O,
N, P
- Nucleotides
- Sugar, phosphate and
nitrogenous base
- Join to form DNA or
single stranded RNA
- DNA stores information that
controls the cell
- DNA transmits inherited
information during cell
division
- RNA is a nucleic acid which
is found in the nucleus and
cytoplasm
- mRNA passes on information
stored in DNA
- tRNA translates messages
carried by mRNA into a
polypeptide chains
Inorganic
substances
Varies
- Minerals (Ca, Zn, Fe)
- Vitamins (A, B, C)
- Helps with metabolism
- Enters the cell as ions
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Document Summary
Eukaryotes have a membrane bound nucleus separated from the cytoplasm: made from one or more cells. Both have a plasma membrane, dna in the form of chromosomes and ribosomes. Region between the membrane and the nucleus. Cytosol is the aqueous fluid that fills the cytoplasm. Chromosome 1 dna molecule and associated proteins. Chromatin total collection of all dna and proteins. Nuclear pores passages where rna and ribosomes pass out of the nucleus and nuclear proteins pass in. Membrane is constant with the rough endoplasmic reticulum. Molecular machines that convert dna carried by messenger. Continuous with the outer membrane of the nuclear envelope. Rough er coated with ribosomes, protein synthesis. Smooth er no ribosomes, lipid synthesis. Packages proteins for transport to the golgi body. Sorts, modifies and packages proteins from the er. Enzymes that breakdown lipids, carbs and proteins into small molecules. Structure separating the inside and outside of the cell. Generates most of the cell"s atp supply.
