DNA to protein

Question 1

What is DNA and what does it stand for?

Answer 1

-deoxyribose nucleic acid
-A polynucleotide which contains genetic information used to create all of the bodies proteins

Question 2

What makes up DNA?

Answer 2

4 nucleotide types make up DNA- guanine, cytosine, adenine, thymine (T and A bind together, C and G bind together)

Question 3

What are the 3 parts that make up DNA?

Answer 3

-Base (nitrogenous)
(purines-guanine and adenine)
(pyrimidines- cytosine and thymine)
-Deoxyribose sugar
-Phosphate group

Question 4

what are the 2 ways nucleotides can bind together?

Answer 4

By phosphate groups
By hydrogen bonds

Question 5

What are a set of 3 bases in DNA/mRNA called and what do they do?

Answer 5

-triplet/codon
-code for a specific amino acid

Question 6

what is the difference between DNA and mRNA?

Answer 6

-DNA can’t exit nucleus
-mRNA can move from the nucleus to the cytosol, allowing genetic information to be moved to the ribosome so a protein can be created

Question 7

what are the structural differences between DNA and mRNA?

Answer 7

-Base- both have nitrogenous bases and same purines however the pyrimidines are different. DNA: cytosine and thymine, mRNA: cytosine and uracil
-Sugar: DNA has deoxyribose sugar, mRNA contains ribose sugar
-Both have phosphate group

Question 8

what is a gene?

Answer 8

a region of DNA that contains the information to make a functional piece of mRNA which can go onto to make a protein

Question 9

what is RNA polymerase?

Answer 9

an enzyme that adds new nucleotides to a growing strand of RNA

Question 10

What are the 2 processes involved in protein synthesis?

Answer 10

Transcription- process of taking a single gene of DNA and copying it into a complementary structure called mRNA
Translation-process of taking mRNA strand and using it to produce a protein

Question 11

Describe the process of transcription?

Answer 11

• RNA polymerase unwinds DNA strands causing bases to become exposed. One strand (coding strand) becomes the template with the genes to be coded
  -polymerase then aligns correct nucleic acid (A,C.G or U) with complementary base on DNA template strand creating complementary mRNA base by base
  -Once polymerase has moved along entire gene and finished making mRNA strand the RNA polymerase detaches from DNA and DNA strands close back up
  -This leaves a mRNA strand that is free to leave the nucleus to go to the ribosome where it can be used to create a protein (translation)

Question 12

What must happen to mRNA before its able to leave the nucleus?

Answer 12

-must be processed into functional mature mRNA by undergoing RNA processing

Question 13

Describe what happens during RNA processing?

Answer 13

-A cap is placed on start end (5 end) of mRNA strand which protects it from being degraded by enzymes
-A stretch of 50-259 adenine bases are added to end of mRNA strand which protects it from degradation and helps to transport it to the cytoplasm
-mRNA contains introns, which are not needed to make a functional protein, so they are removed and the final mature mRNA can move out the nucleus to the cytoplasm

Question 14

Describe the process of translation?

Answer 14

-mRNA strand and ribosome bind together so that the ribosome can begin building protein by adding amino acids
-Amino acids are brought to ribosome by molecules called tRNA (transfer RNA); tRNA have amino acid at top of structure and an anticodon (sequence of 3 bases which are complimentary to bases on mRNA strand) at the bottom
-Anticodons on tRNA pair with bases on mRNA, allowing the correct amino acids to be brought to the ribosomes in the correct order
-This allows for the ribosomes to join the amino acids together, building up a chain
-This continues until the ribosome finishes moving along the mRNA chain until a chain of amino acids is complete (each time a new tRNA molecules attaches to mRNA the first molecule detaches)
-The amino acid chain then detaches from ribosome and can fold up on itself to form a protein

Question 15

what are the different types of RNA and what are their functions?

Answer 15

-mRNA- encodes proteins
-tRNA- acts as adaptor between mRNA and amino acids
-rRNA- forms the ribosome
-snRNA- functions in various nuclear processes
-snoRNA- facilitates chemical modification of RNA’s
-miRNA- regulates gene expression
-siRNA- silences gene expression
-IncRNA- regulates gene expression

Question 16

What are exons and introns within the human gene?

Answer 16

-exon-portion of gene that contains DNA sequence that will be translated into protein.
-Intron-portion of gene that will be cut out before translation

Question 17

Describe the DNA variability within human genome?

Answer 17

-more than 400 million variants in human genome
-3% are frequent in population and are called polymorphisms

Question 18

What can genetic change lead to?

Answer 18

-differences in the protein structure
-differences in level of gene expression

Question 19

what is methylation?

Answer 19

-a chemical modification of DNA that can alter gene expression
-unused genes undergo methylation (2 states- hypomethylation and hypermethylation)

Question 20

what are the 3 types of genes that may be expressed in muscle fibres?

Answer 20

Type 1- slow- MYH7 gene (contains ACTN2 protein)
Type 2a- fast- MYH2 gene (Contains ACTN3 protein)
Type 2x- fastest- MYH1 gene

Question 21

what factors effect the expression of MYH7, MHYH2 and MYH1 gene in muscle fibres?

Answer 21

-sex (more slow in women)
-age (more slow in older people)
-type of training
-nutrition
-gene polymorphisms

Question 22

what is ACTN3 protein and why is it beneficial?

Answer 22

-found in z-lines of fast-twitch muscle fibres
-is hypermethylated in response to endurance training]-15-20% of Europeans have a genotype that results in complete absence of this protein

Question 23

what are the factors that can affect gene expression in humans?

Answer 23

-Nutrition
-Duration and type of exercise
-stress
-harmful habits (smoking, alcohol)
-Environment (air/ water pollution)