Biology Flashcards
3 principles of cell theory
1) all living things are made up of one or more cells
2) cells are the most basic unit of structure and function
3) all cells are created by pre-existing cells
Name the 2 types of cells
Prokaryotic = bacteria
Eukaryotic = animal and plant cells
Eukaryotic cells
- have membrane bound organelles (mitochondria or cytoplasms)
- DNA contained within the nucleus
Prokaryotic cells
- DNA floats freely in the cytoplasm or is found as small circular molecules known as plasmids
Plasma membrane
- Found around the outside of the cell
- Consists of a phospholipid belayer together with proteins and other components
- Controls entry and exit of the substances in and out of the cell
Nucleus
-
Gene
A sequence of bases in DNA that codes for a polypeptide (chain of amino acids)
What does each nucleotide contain
-a pentose(5 carbon sugar)
-a nitrogen containing organic base
-a phosphate group
RNA base pairs
-adenine (A)
-cytosine (C)
-guanine (G)
-uracil (U)
How are nucleotides joined
In long chains by phosphodiester bonds between the pentose sugars (described as sugar phosphate backbone)
Stages of DNA replication
-the DNA double helix is progressively unwound. This involves an enzyme (helicase) that breaks the hydrogen bonds between the bases
-each strand now has unpaired bases
-the strands each act as templates to assemble new strands. DNA nucleotides bund to the unpaired bases through complementary base pairing
-the enzyme DNA polymerase catalyses the formation of the phosphodiester bonds between the nucleotides
Mutation
A change in the sequence of bases in DNA. this can occurs in a number of ways. When a mutation occurs within a coding region of DNA a new allele can be formed
Allele
A variant of a gene
Genetics
The study of how single genes or a small group of genes function and how they affect the appearance and functioning of the organism
Genomics
The study of how all the genes in an organism interact as well as the role of non coding sequences if DNA
Genome
The entire genetic material of an organism. This includes DNA that doesn’t code for proteins as well as the coding DNA (genes)
Difference between RNA AND DNA
RNA - the pentose is ribose
DNA - the pentose is deoxyribose
Genetics allows us to
Understand how inherited disorders are passed on
Genomics is used to
Investigate the link between all the genes we carry and the development of a wide range of diseases and conditions
Bacteria
-typically 1-2 micrometers long
-cylindrical
-don’t have membrane bound organelles
-prokaryotes
Fungi
-between 4-12 micrometers
-eukaryotes
-do have membrane bound organelles
Parasites
-lives on or in another organism
-single celled eukaryotic
-range 1-10 micrometers
Viruses
-acellular
-range 20-200 nanometers
-consist of DNA or RNA
Magnification
How much bigger the image is than the actual object we are viewing
Resolution
The ability of a microscope to distinguish between two adjacent points
Light and electron microscopes
Light microscopes use glass lenses
Electron microscopes use magnets as lenses
Light microscope
-inexpensive
-easy to use
Scanning electron microscope
The beam of electrons is scanned across the surface of the sample
Transmission electron microscopes
In a transmission electron microscopes the electrons pass through the sample in the same way as light rays pass through a sample in the light microscope
Micrometer
10^-6
Nanometer
10^-9 M
How to calculate magnification
Magnification = size of image (divided by) size of object
Gram staining
Giemsa staining
Haematoxylin and eosin staining
Bacteria diseases
-chlamydia
-gonorrhoea
-tuberculosis
Treated by antibiotics
Viruses diseases
-common colds
-mumps
-measles
Fungi diseases
-yeast infection (thrush)
Toenail fungus and athletes foot
Prions diseases
-Creutzfeodt -Jakob disease (CJD)
Prions are non living pathogenic proteins
Protoctists diseases
Malaria
Parasites disease
-toxoplasmosis
Direct transmission
-physical contact with an infected person or contaminated surface
-sharing of needles can result in transmission of blood borne pathogens
-pathogens such as HIV can be spread through transfusion with contaminated blood
Airborne transmission
The pathogen is carried by dust or droplets in the air. Some droplets can exists in the air for many hours and inhaling infected droplets can lead to infection
Indirect transmission
-vehicle transmission occurs when infected food or water are ingested
-bitten by a vector, insect bites can introduce pathogens into the body
Inadequate sanitation includes
-a lack of access to clean water for washing. Unclean water is likely carry water borne diseases
-inadequate sewage disposal, increases the risk of faecal oral transmission of a wide range of pathogens
Antigen
A substance that is recognised by the immune system as self or non self and simulates an immune response. Antigens are found on pathogens but also on the surface of all body cells
Antibody
A blood protein that is produced in response to a specific antigen. An antibody binds specifically to an antigen in a similar way to an enzyme binding specifically to its substrate
Physical and chemical barriers
The skin is a physical barrier to keep pathogens out
Mucous membranes line the gut, airways and reproductive system
Goblet cells produce thick sticky mucous to trap bacteria and other pathogens
Lysozyme is an enzyme that hydrolyses bonds in the cell wall components of some bacteria. This weakens the cell walls meaning that the bacteria swell and burst. Lysozyme is present in tears, helping to protect the surface of the eyes, as well as in breast milk
Nucleus (containing chromosomes)
-contains genetic information
-surrounded by the nuclear envelope
-has many gaps/pores
-has chromatic - coiled and super coiled to form the chromosomes
Mitochondria
-aerobic respiration
-adenosine triphosphate (ATP) production
-inner membrane is folded into structures (Cristae)
Ribosomes
-protein synthesis
-mRNA to assemble the correct order of amino acids
Rough and smooth endoplasmic reticulum
-ER is a system of membrane bound flattened sacs that fills a large part of the chromosome
-RER has ribosomes attached to its outer surface
-smooth ER doesn’t have attached ribosomes and is responsible for synthesising, storing and transporting lipids and some carbohydrates
Golgi apparatus and Golgi vesicles
Chloroplasts (in plants)
How prokaryotic cells differ from eukaryotic cells
-smaller ribosomes
-no nucleus
-1 or more plasmids
-may have a capsule surround cell
-may have 1 or more flagella
-have a cell wall
-have cytoplasm that lacks membrane bound organelles
