Lecture V: Proteins, Nucleic Acids, and protein synthesis

Question 1

Functions of proteins?

Answer 1

Speed up chemical reactions (Enzymes)

Defense

Storage

Transportation

Chemical messengers (Hormones)

Receptors

Movement

Structural

Question 2

What are the proteins that accelerate chemical reactions?

Answer 2

Enzymes, highly specific to its substrate and cannot facilitate other reactions.

Question 3

Describe the role of defense.

Answer 3

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.

Question 4

Describe the role of storage

Answer 4

Storage of amino acids for development.

Question 5

Describe the role of transportation

Answer 5

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.

Question 6

Describe the role of chemical messengers

Answer 6

Many proteins are hormones.

Question 7

Describe the role of receptors

Answer 7

Receptors on cell membranes that bind specific hormones or neurotransmitters are proteins.

Question 8

Describe the role of movement.

Answer 8

Muscle cells contain protein fibers that slide across each other to cause the muscle to contract and relax.

Question 9

Describe the tole of structural support.

Answer 9

Proteins can be a structural material for organisms. such as silk, etc.

Question 10

What is the structure of a protein?

Answer 10

Made of amino acid monomers, containing an amino group (nitrogen), a carboxyl group, and an fucional group.

Question 11

How are proteins formed?

Answer 11

Through Dehydration synthesis.

Question 12

What are the 4 structural levels of proteins? Why is the shape so important?

Answer 12

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.

Question 13

What is protein denaturation? What causes it? Why is homeostasis important?

Answer 13

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

Question 14

What are the two types of nucleic acids? What is the structure?

Answer 14

Two kinds:

1. DNA (DeoxyriboNucleic Acid)
2. RNA (RiboNucleic Acid)

Structure: Polymers made up of many nucleotides (monomers) bonded together in a long chain.

Question 15

What are the three components of nucleotides?

Answer 15

Sugar molecule
Phosphate molecule
Nitrogenous base

Question 16

What are the main differences between DNA and RNA?

Answer 16

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.

Question 17

What is DNA? Where is it found?

Answer 17

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).

Question 18

What are the 4 nitrogenous bases? What are the two pairs?

Answer 18

Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
A goes with T
G goes with C

Question 19

DNA functions?

Answer 19

1. Makes up our genes, the instructions for making proteins, essential to the cell’s life.
2. Replication and division of DNA occurs to make new copies of cells for growth and repair (Mitosis).
3. Transmit genes to offspring (Meiosis). Making sperm and eggs

Question 20

What is the change in the nitrogenous bases that RNA has?

Answer 20

Thymine becomes Uracil (U)

Question 21

What are the two roles of RNA?

Answer 21

1. RNA is a transcribed copy of a gene sequence from the DNA in the nucleus.
2. Some RNA is translated into amino acid sequence to make a particular protein with the help of ribosomes in the cytoplasm.

Question 22

What are the two MAJOR steps of protein synthesis?

Answer 22

1. 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
2. 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.

Question 23

What are the three types of RNA?

Answer 23

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.

Question 24

What is a Codon?

Answer 24

A sequence of three nitrogenous bases on an mRNA that code an amino acid (UAU or UCU)

Question 25

Review all the steps for the protein synthesis.

Answer 25

lol