Properties of Proteins Flashcards
What do proteins determine
- nature of species
- colour of hair, eyes, skin, etc
- whether a cell is muscle, nerve, epithelial or any other
What does each protein consist of
A unique sequence of amino acids and a unique 3D shape
When is the role of proteins important
information coded into the molecular structure of DNA.
How are proteins different from other molecules
They can bind organic molecules and ions selectively
What is a ligand
Any molecule or ion that is bound to the surface of another molecule (protein) by forces other than covalent bonding. e.g. electric attraction
How does a ligand work
It binds to specific chemical groups on a small area of the protein surface (binding site). Protein binding depends very much on shape - chemical specificity.
What are the functions of protein binding sites
- Holding cells together
- Catalysing the chemical reactions in cells (enzymes)
- Communication between different systems of the body (e.g. hormones)
What is a gene
The portion of DNA that contains the information required for transmission
What is a function of DNA
The transmission of hereditary information from cell to cell. Contains instructions for the synthesis of proteins coded into its molecular structure.
Describe the characteristics of DNA
- 2 polynucleotide chains coiled around each other to form a double helix
- 1 molecule of DNA contains the genetic information corresponding to many different proteins arranged as a sequence of genes
- most of a cell’s DNA is in the nucleus
How is genetic information transferred to protein?
1) Code carried from DNA to the ribosome in the cytoplasm by RNA
2) Transfer RNA binds & escorts specific amino acids to the ribosome to place each in the correct order dictated by the triplet sequence in messenger RNA
DNA –> RNA –> PROTEIN
How is genetic information replicated (cell reproduction)
For growth of an organism, cells must divide and replicate. Genetic info stored in DNA must be formed and passed onto daughter cells.
What is cell replication generally carried out by?
Undifferentiated or stem cells
What is mutation
Mistakes in the replications of DNA
How can mutations be advantageous?
- Evolution of living organisms
- Basis of natural selection
How can mutations be disadvantageous?
- Less effective function
- Death of the cell by carrying the mutant gene
What are the 3 periods that occur during the division of any reproductively active cell?
- Interphase
- Mitosis
- Cytokinesis
Describe the interphase period
- Longest phase & is the time between cell division
- The phase where major bodily functions are carried out
- Most cells are in the interphase state
How many long chromatin threads does the interphase nucleus contain
46 (half from male and half female)
What is mitosis?
The process of separating the 46 chromatin threads in each cell nucleus, to produce 2 identical sets of chromosomes in two separate nuclei.
- Provides the daughter cells with an identical set of DNA molecules
What is Cytokinesis?
The process in which the cytoplasm of a single cell is divided to form two daughter cells
What are the 4 types of cell tissues?
Epithelial, connective, muscular, nervous
What is epithelial tissue for?
Protection, absorption, secretion, extretion
What is connective tissue for?
support, packing material, defence
