lecture 6: biomolecules part 2 Flashcards
What is a protein?
Biologically functonal molecule that consists of one or more polypeptides + associated cofactors
- Very diverse functions
What are do proteins do? (8 functions)
- Enzymatic proteins: biological catalysts —> accelerate chemical reactions
- Defensive proteins: protection against infection, disease, other life-threatening events
- Storage proteins: storage of amino acids
- Transport proteins: transport of substances around the body in and out of cells
- Regulatory proteins: regulate cellular activities (cell division)
- Communication proteins: response of cell stimuli and communication between cells
- Motor proteins: movement of body, cell or components in cells
- Structural proteins: production of structural components —> provide support and protection
What are polypeptides?
Unbranched polymers built from same set of 20 amino acids
What are amino acids and what do they constist of?
- Organic molecules with carboxyl and amino groups + Side chain (R group)
- All amino acids = same amino group and carboxyl group, but differs in R group
What are the 3 major classes of amino acids?
- Difference in the R group*
1. Nonpolar (hydrophobic): C-H bonds = nonpolar covalent bonds
2. Polar Uncharged (hydrophilic): O-H, N-H = polar, but no charges
3. Charged acidic/Charged basic (hydrophilic): acidic = negative charge and basic = positive charge
What is proteins’ primary structure?
1 polypeptide chain —> repeating amino acids joinded by peptide bonds with side chains hanging on the side
What are proteins’ higher levels of structure?
Tieriary structure (&secondary = the different subsections) Quaternary (not all attain this level)
What consists of a functional protein?
Consists of one or more polypeptides precisely twisted, folded, and coiled into a unique shape
Are proteins diverse in structures?
Yes. As “structure fits functions” and as proteins are very diverse in functions, they are also diverse in structures. Proteins are the most structurally diverse class of molecules known.
What is sickle-cell disease?
- Genetic blood disease that results from a single amino acid substitution in one polypeptide of the protein hemoglobin.
- Usually, the molecules of a normal hemoglobin do not associate with each other as they carry oxygen. The red blood cell is smooth and caved in, allowing it to travel in blood vessels.
- The molecules of a sickle-cell hemoglobin crystallize into a fiber causing its capacity to carry oxygen to be reduced. The red blood cell’s structure is compromised and does not allow it to travel smoothly in blood vessels.
What is the consequence of a slight change in the sequence of amino acids in a polypeptide (the primary structure)?
A slight change in the primary structure can affect all of a protein’s higher levels of structure and its ability to function
How do changes to the physical and chemical environment affect a protein’s structure?
Can interfere with bonds that form upper level structures of a protein and cause a protein to come apart (denaturation)
What is denaturation and renaturation?
- Loss of protein’s natural structure —> misfolding of the protein
- Can be reversible or irreversible depending on magnitude of change
- Renaturation = protein regains natural structure
- A denatured protein is biologically inactive.
What is a nucleic acid and what does it consists of?
- Genetic material in all cells (and viruses)
- Also many are functional molecules with many important functions in cell
- Composed of one or more unbranched polymers called “polynucleotides”
What are the 2 types of nucleic acids?
- Deoxyribonucleic acid (DNA)
2. Ribonucleic acid (RNA)
What does DNA do (5 elements)?
- Acts as genetic material in all cells that can…
- Carry information
- Be replicated
- Be transmitted to offspring (genetic & heredity)
- Be changed by mutation (genetic diseases)
What informations (3) is in DNA?
- Directions for its replication
- Units called genes that encode sequence of specific polypeptides and other gene products
- Directions for using genes
What do genes do?
Expression of our genes in a genetic program gives rise to our development program which gives us our species’ chracters & indivudal traits
- Genes are heritable units passed on to our offspring
What does RNA do (3 main functions)?
RNA = big players in gene expression
- Messenger RNA (mRNA): copied from genes + provide information for translation of a nucleic acid sequence into a polypeptide sequence
- Ribosomal RNA (rRNA): makes up part of the ribosome (protein synthesis machinery)
- Transfer RNA (tRNA): adaptor molecules in protein synthesis
What are the steps of gene expression?
- DNA (gene)
Transcription in nucleus - Synthesis of mRNA —> mRNA
Movement of mRNA into cytoplasm
Translation of nucleic acid sequence into polypeptide sequence (with ribosomes and tRNA) - Synthesis of protein —> Protein (polypeptide)
What are polynucleotides made of?
Polynucleotide is made of monomers called nucleotides
What are the 4 different types of nucleotides in DNA and in RNA?
DNA: Cytosine (C), Guanine (G), Adenine (A), and THYMINE (T)
RNA: Cytosine (C), Guanine (G), Adenine (A), and URACIL (U)
Nucleotide structure?
- Phosphate group
- 5-carbon sugar (Ribose in RNA and Deoxyribose (lose oxygen) in DNA)
- Nitrogeous bases (ATCG for DNA and AUCG for RNA)
DNA structure?
- 2 polynucleotides spiraling around forming a double helix
- Double hexlix held together by complementary base pairing (by noncovalent bonds as it is easier to separate without damage)
