UofM Biology DNA and Protein Synthesis Worksheet This is a lab assignment, detailed questions are post in the attached file. Need to finish Part 1 until Pa

UofM Biology DNA and Protein Synthesis Worksheet This is a lab assignment, detailed questions are post in the attached file. Need to finish Part 1 until Part 4

Here is part of question 1 for brief look if you can work this assignment or not.

The goals of this lab are:

1.To gain a basic understanding of the structure of DNA, RNA, and Proteins.

2.To gain a basic understanding of DNA replication and protein synthesis.

Introduction

This lab describes the structures and functions of DNA and RNA, the chemical molecules that carry hereditary information from generation to generation and allow it to be used in building and running the bodies of living things.

Terms you need to know for this lab:

Codon: Three mRNA bases that specify an amino acid.

Anticodon: tRNA that bases that match Codon.

Nucleotide: Basic unit of DNA or RNA: a sugar, a phosphate, and a base.

Base Pair: A nucleotide and its paired opposite in DNA, used as a measure of length in DNA.

Amino Acid: component of a protein.

Polypeptide Chain: A string of amino acids.

Genetic Code: List of codons and the amino acids they code for.

Gene: DNA sequence that codes for a protein.

Part 1: DNA Structure – Storage of Information

The simplest functional subunit of DNA (Deoxyribonucleic acid) is called a nucleotide, ‘nucleo’ referring to the nucleus, and ‘tide’ meaning a division. A nucleotide is made up of: 1) one phosphate molecule (P); 2) one sugar molecule,called deoxyribose (S); and 3) one nitrogenous base (B).

Phosphate

B

Sugar

B Base

Figure 1. Schematic diagram of the structure of a nucleotide. A nucleoside is a subdivision of a nucleotide that consists of one nitrogenous base bonded to one sugar, but lacks the phosphate. ANTHROPOLOGY 170, LAB 2
DNA AND PROTEIN SYNTHESIS
The goals of this lab are:
1.
To gain a basic understanding of the structure of DNA, RNA, and Proteins.
2.
To gain a basic understanding of DNA replication and protein synthesis.
Introduction
This lab describes the structures and functions of DNA and RNA, the chemical molecules that carry
hereditary information from generation to generation and allow it to be used in building and running the
bodies of living things.
Terms you need to know for this lab:
Codon: Three mRNA bases that specify an amino acid.
Anticodon: tRNA that bases that match Codon.
Nucleotide: Basic unit of DNA or RNA: a sugar, a phosphate, and a base.
Base Pair: A nucleotide and its paired opposite in DNA, used as a measure of length in DNA.
Amino Acid: component of a protein.
Polypeptide Chain: A string of amino acids.
Genetic Code: List of codons and the amino acids they code for.
Gene: DNA sequence that codes for a protein.
Part 1: DNA Structure – Storage of Information
The simplest functional subunit of DNA (Deoxyribonucleic acid) is called a nucleotide, ‘nucleo’
referring to the nucleus, and ‘tide’ meaning a division. A nucleotide is made up of: 1) one phosphate
molecule (P); 2) one sugar molecule,called deoxyribose (S); and 3) one nitrogenous base (B).
P
S
P
Phosphate
S
Sugar
B
B
Base
Figure 1. Schematic diagram of the structure of a nucleotide. A nucleoside is a subdivision of a
nucleotide that consists of one nitrogenous base bonded to one sugar, but lacks the phosphate.
1
There are four different types of nucleotides. All have the same sugar (deoxyribose) and the same
phosphate, but differ in the type of base. There are four different types of bases:
Figure 2. Four types of bases that form nucleotides.
A single strand of DNA consists of many nucleotides linked together by strong chemical bonds
between the phosphate and sugar molecules to form a polynucleotide chain; ‘poly’ meaning many. A
DNA molecule is made up of 2 polynucleotide chains which are complementary. The 2 chains are
linked together by weak chemical bonds (called hydrogen bonds) between 2 bases, one base from each
chain (Figure 2). The 2 bases fit together like puzzle pieces, but not all bases bond together. Only
particular bases bond together:
1.
2.
Adenine bonds only with thymine (A–T) with 2 hydrogen bonds.
Cytosine bonds only with guanine (C–G) with 3 hydrogen bonds.
Nitrogenous Bases
A
T
Deoxyribose Sugar Molecule
C
G
Phosphate Molecule
G
T
C
A
Weak bonds between bases
Figure 3. Schematic diagram of part of a DNA molecule.
2
Be sure to examine the three-dimensional model of DNA structure, available online at the following
address: https://proteopedia.org/wiki/index.php/DNA.
Part 2: DNA Replication – Transfer of Information
DNA has 2 functions — both storage and transfer of information. To accomplish these functions DNA
must be able to replicate itself. There are 2 separate times when DNA must replicate. Because DNA is
carried in the chromosomes which are present in every cell of the body, DNA must replicate during
mitosis and meiosis. The replication process can be explained in the following way:
1.
2.
3.
4.
The hydrogen bonds between the bases break, causing the 2 chains of DNA to separate.
Free DNA nucleotides, which are always present in the nucleus, bond to the exposed bases of
both chains.
These new nucleotides bond together to form new polynucleotide chains.
Two new, identical double-stranded DNA molecules result, which then “twist” and form two
double helices.
This process is illustrated schematically below.
Figure 4. Diagram of DNA replication.
3
1. Illustrate the major steps in replication, using the schematic drawing of a DNA molecule given
below. The phosphate and sugar units are not included to make this easier to draw. See figure 3 as
an example. Each of the following steps require a separate drawing:
A) show how the strands separate, and how new nucleotides attach to the exposed bases.
B) Show the resulting 2 new DNA molecules.
Original DNA
A)
B)
sense T–A
T–A
A–T
G–C
G–C
C–G
T–A
G–C
A–T template
Part 3: Protein Synthesis.
DNA acts as a ‘code’ or ‘blueprint’ for protein synthesis — the making of proteins. Proteins are made up
of amino acids linked together by peptide bonds. Therefore, proteins are also called polypeptide chains.
There are 20 different kinds of amino acids found in proteins. It is the sequence of the bases in a DNA
molecule which codes for the sequence of amino acids that make up a protein. There are 2 steps involved
in the synthesis of proteins, transcription and translation.
Transcription. This step occurs inside the nucleus of a cell. A molecule of RNA (ribonucleic acid) is
constructed alongside a DNA molecule, using the DNA as a template. As in replication, the two DNA
strands separate. Then, free RNA nucleotides (ribonucleotides pair with bases on one of the DNA
strands, called the template strand. The ribonucleotides bond to each other, forming a polynucleotide
chain of RNA. Then the RNA strand breaks away from the DNA strand and leaves the nucleus. This
RNA strand is known as messenger RNA (mRNA).
The other DNA strand is called the sense strand. It is called the sense strand because when the mRNA
is completed it will look similar to the sense strand with 2 exceptions:
1) RNA nucleotides have a different sugar (ribose);
2) in RNA the base uracil (U) is substituted for thymine (T). Uracil, like thymine, bonds with adenine
(U–A).
4
Another difference between DNA and RNA is the fact that RNA is single-stranded and as you know
DNA is double-stranded. If any of this is unclear look in the textbook (pg. 65-67) or ask your lab
instructor.
Translation. The mRNA travels outside of the nucleus to an area of the cell cytoplasm where structures
called ribosomes are found. A series of 3 ribonucleotides on mRNA is called a codon. Each codon codes
for a specific amino acid. Remember amino acids are the building blocks of proteins.
Another kind of RNA, transfer RNA (tRNA), carries the amino acids to the mRNA strand. The tRNA
has an amino acid on one end and a series of 3 ribonucleotides (called an anticodon) on the other end.
As a ribosome travels over the mRNA, the tRNA anti-codons bond with corresponding mRNA codons.
Because the tRNA molecules are carrying amino acids, this process of codon-anticodon pairing brings a
series of amino acids together. The amino acids bond with each other, forming a polypeptide chain
which then breaks away from the tRNA molecule. The tRNA molecules will then break away from the
mRNA molecule.
1.
For this exercise use the sequence of bases from the DNA molecule portrayed in the previous
problem (“DNA Replication”). Note that one strand is the ‘sense’ strand and the other the ‘template’
strand. Fill in the blanks with the appropriate bases as if the DNA molecule from exercise 1 were used
to synthesize a protein. Next, use the genetic code at the end of this lab to fill in the appropriate amino
acids coded for by this gene.
sense strand:
A ___ ___ ___ ___ ___ ___ ___ ___
template strand:
___ ___ ___ ___ ___ ___ ___ ___ ___
mRNA (codons):
___ ___ ___ ___ ___ ___ ___ ___ ___
tRNA (anti-codons): ___ ___ ___ ___ ___ ___ ___ ___ ___
amino acids:
___________ __________
5
____________
Part 4: Mutation
A mutation is a change in the DNA sequence of an individual. The simplest type of mutation is a point
mutation. This is where a single base in the sequence is swapped for another, such as G changing to C.
If a mutation occurs in a segment of DNA that does not code for a protein (or any other gene product),
then it is a “neutral” mutation, because it does not change the phenotype. Other mutations may occur in
the coding region of a gene. Since many codons code for the same amino acid (e.g. UUU and UUC), a
mutation may result in a change in the DNA, but not the resulting polypeptide chain. When this occurs,
it is termed a “synonymous mutation” because even though the DNA has changed, the organism’s
phenotype has not. Many mutations, however, result in a change in the polypeptide chain. This in turn,
can change the resulting protein, and thus the phenotype of the individual. If the mutation occurs in a
gamete (i.e. sperm or egg), then it could be passed on to the offspring of that individual, and then become
a new allele in the gene pool of that population. Mutation, therefore, is important as a source of new
variation within populations.
1.
In human red blood cells, the protein hemoglobin is responsible for binding oxygen to red blood
cells so that it can be carried throughout the body to be used in cellular respiration. In a normal
hemoglobin strand the polypeptide sequence (for amino acids number 5-8 of the beta chain) is: proline
– glutamic acid – glutamic acid – lysine.
a) The DNA coding sequence for normal hemoglobin is:
G
b) The mRNA codons are:
G
A
C
T
C
C
T
C
T
T
T
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
c) The tRNA anti-codons are: ___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
The disease sickle cell anemia, is a defect in the hemoglobin molecule. In sickle cell individuals, the
amino acid sequence is: proline – valine – glutamic acid – lysine. This difference is the result of a point
mutation in the sequence above.
6
Using the genetic code at the end of this lab, spell out the DNA coding sequence for the sickle cell
hemoglobin:
d) The DNA coding sequence for sickle cell hemoglobin:
___ ___ ___
___ ___ ___
___ ___ ___
___ ___ ___
The Genetic Code
UUU – phenylalanine
UUC – phenylalanine
UCU – serine
UCC – serine
UAU – tyrosine
UAC – tyrosine
UGU – cysteine
UGC – cysteine
UUA – leucine
UCA – serine
UAA – stop
UGA – stop
UUG – leucine
UCG – serine
UAG – stop
UGG – tryptophan
CUU – leucine
CCU – proline
CAU – histidine
CGU – arginine
CUC – leucine
CCC – proline
CAC – histidine
CGC – arginine
CUA – leucine
CCA – proline
CAA – glutamine
CGA – arginine
CUG – leucine
CCG – proline
CAG – glutamine
CGG – arginine
AUU – isoleucine
ACU – threonine
AAU – asparagine
AGU – serine
AUC – isoleucine
ACC – threonine
AAC – asparagine
AGC – serine
AUA – isoleucine
ACA – threonine
AAA – lysine
AGA – arginine
AUG – methionine
ACG – threonine
AAG – lysine
AGG – arginine
GUU – valine
GUC – valine
GCU – alanine
GCC – alanine
GAU – aspartic acid
GAC – aspartic acid
GGU – glycine
GGC – glycine
GUA – valine
GCA – alanine
GAA – glutamic acid
GGA – glycine
GUG – valine
GCG – alanine
GAG – glutamic acid GGG – glycine
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