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