Lecture V: Proteins, Nucleic Acids, and protein synthesis Flashcards
Functions of proteins?
Speed up chemical reactions (Enzymes)
Defense
Storage
Transportation
Chemical messengers (Hormones)
Receptors
Movement
Structural
What are the proteins that accelerate chemical reactions?
Enzymes, highly specific to its substrate and cannot facilitate other reactions.
Describe the role of defense.
Antibodies are proteins created by our immune system that adhere to antigens (e.g. Bacteria) and act as beacons for macrophages to come and destroy them.
An antibody is highly specific and can only adhere to one type of antigen.
Describe the role of storage
Storage of amino acids for development.
Describe the role of transportation
Transportation of oxygen in the blood by hemoglobin proteins within red blood cells.
There are many proteins embedded in the plasma membrane of cells. Some of which allow the passage of specific substances.
Describe the role of chemical messengers
Many proteins are hormones.
Describe the role of receptors
Receptors on cell membranes that bind specific hormones or neurotransmitters are proteins.
Describe the role of movement.
Muscle cells contain protein fibers that slide across each other to cause the muscle to contract and relax.
Describe the tole of structural support.
Proteins can be a structural material for organisms. such as silk, etc.
What is the structure of a protein?
Made of amino acid monomers, containing an amino group (nitrogen), a carboxyl group, and an fucional group.
How are proteins formed?
Through Dehydration synthesis.
What are the 4 structural levels of proteins? Why is the shape so important?
Primary – specific sequence of amino acids in chain
Secondary – Folding and coiling of sections of the chain
Tertiary – Conformational shape of whole polypeptide chain
Quaternary – When more than one polypeptide chain come together to form the protein.
The final structural shape of a protein is critical for it to function normally.
What is protein denaturation? What causes it? Why is homeostasis important?
Proteins are fragile
If they lose their 3D structure (unravel) they become non-functional (denatured). Heat, or changes in salinity, or pH can cause denaturation. -> importance of homestasis
What are the two types of nucleic acids? What is the structure?
Two kinds:
- DNA (DeoxyriboNucleic Acid)
- RNA (RiboNucleic Acid)
Structure: Polymers made up of many nucleotides (monomers) bonded together in a long chain.
What are the three components of nucleotides?
Sugar molecule
Phosphate molecule
Nitrogenous base
What are the main differences between DNA and RNA?
DNA is double stranded
It has 2 long polynucleotide strands linked together by hydrogen bonds between their nitrogenous bases.
looks like a twisted ladder.
RNA is single stranded
- It has 1 long polynucleotide strand that twists around itself.
What is DNA? Where is it found?
DNA contains the instructions to make proteins which determine the characteristics of a living organism.
Found within the nucleus of eukaryotic cells and free within the cytoplasm of prokaryotic cells (nucleoid region).
What are the 4 nitrogenous bases? What are the two pairs?
Adenine (A) Thymine (T) Cytosine (C) Guanine (G) A goes with T G goes with C
DNA functions?
- Makes up our genes, the instructions for making proteins, essential to the cell’s life.
- Replication and division of DNA occurs to make new copies of cells for growth and repair (Mitosis).
- Transmit genes to offspring (Meiosis). Making sperm and eggs
What is the change in the nitrogenous bases that RNA has?
Thymine becomes Uracil (U)
What are the two roles of RNA?
- RNA is a transcribed copy of a gene sequence from the DNA in the nucleus.
- Some RNA is translated into amino acid sequence to make a particular protein with the help of ribosomes in the cytoplasm.
What are the two MAJOR steps of protein synthesis?
- Transcription: In order to make a protein, a copy of the nucleotide sequence (length of the gene) must be made. This is called Transcription. The copy is a messenger RNA strand (mRNA). Only the Template strand sequence is copied
- Translation: The nucleotide sequence of the mRNA strand is then translated with the help of a ribosome into amino acid sequence of the desired protein.
What are the three types of RNA?
Messenger RNA (mRNA): An RNA copy of a gene. The instructions followed in the cytoplasm to build the correct polypeptide sequence for a protein. Ribosomal RNA (rRNA): An RNA molecule together with protein molecules make up ribosomes. The site of protein synthesis in the cytoplasm. Transfer RNA (tRNA): An RNA molecule that assists with the translation of the nucleotide sequences of mRNA into amino acid sequences of proteins by providing the correct amino acids.
What is a Codon?
A sequence of three nitrogenous bases on an mRNA that code an amino acid (UAU or UCU)
