ATAR Human Biology - Unit 2 Exam with
correct Answers
Adenine, guanine, cytosine, thymine ANSWERS Nitrogenous bases
DNA ANSWERS In the form of long strands about 2-3m long
- Consists of two strands of alternating sugar and phosphate groups with pairs or
nitrogen bases forming cross-lines between strands
Nucleotide ANSWERS Each phosphate group and sugar molecule with a nitrogen
base attached
Structure of Chromosomes - Chromosomes ANSWERS When a cell is dividing
the coiled chromatin becomes even more tightly coiled and become chromosomes
Messenger RNA ANSWERS is made in the nucleus and takes the genetic code
into the cytoplasm allowing the genetic code to be read by ribosomes
Ribosomal RNA ANSWERS makes up apporximately 60% of the mass of
ribosomes with the other 40% being protein. The rRNA ensures the correct alignment of
mRNA, tRNA and ribosome. It also has an enzymatic role in the formation of peptide
bonds between the amino acids
Mitochondrial DNA ANSWERS The organelles in the cell where the aerobic phase
of respiration occurs, releasing energy for use by the cell. It is in the form of small
circular molecules hat are not bound to proteins. There are about 5 - 10 molecules of
mtDNA in each mitochondrion. It has 37 genes all of which are essential - Nuclear DNA
is in the form of very long strands that are bound to proteins, the histones
Inheritance of mitochondrial DNA ANSWERS Normally inherited exclusively from
the mother
- The mitochondria in mammalian sperm are usually destroyed after fertilisation
Transcription - Step 1 ANSWERS Is the process by which the genetic instructions
are copied from the DNA to the mRNA molecule. The transcription is triggered by
chemical messengers that enter the nucleus from the cytosol and bind to the DNA at the
relevant gene. This causes an enzyme called RNA polymerase to being the process of
making mRNA. The helicase enzyme makes the double stranded DNA molecule come
apart. It usually seperates about 17 base pairs at a time. RNA polymerase then
transcribes the bases on one strand of the DNA to make a complementary molecule of
, mRNA. At the end of the gene, a seqeunce of bases tells the RNA polymerase to stop
copying and as a result the mRNA molecule is released. The strand that is copied is
called the template strand because it is the template from which the mRNA is made.
The other DNA strand is known as the coding strand
Transcription - Step 2 ANSWERS The helicase enzyme makes the double
stranded DNA molecule come apart. It usually seperates about 17 base pairs at a time.
RNA polymerase then transcribes the bases on one strand of the DNA to make a
complementary molecule of mRNA. At the end of the gene, a seqeunce of bases tells
the RNA polymerase to stop copying and as a result the mRNA molecule is released.
The strand that is copied is called the template strand because it is the template from
which the mRNA is made. The other DNA strand is known as the coding strand
Transcription - Step 3 ANSWERS RNA polymerase then transcribes the bases on
one strand of the DNA to make a complementary molecule of mRNA. At the end of the
gene, a seqeunce of bases tells the RNA polymerase to stop copying and as a result
the mRNA molecule is released. The strand that is copied is called the template strand
because it is the template from which the mRNA is made. The other DNA strand is
known as the coding strand
Transcription - Step 4 ANSWERS The strand that is copied is called the template
strand because it is the template from which the mRNA is made. The other DNA strand
is known as the coding strand
Translation - Step 1 ANSWERS The production of a protein using the information
that is coded into the mRNA molecule
In the cytosol, a ribosome attaches to one end of the mRNA molecule at a particular
sequence of bases (adenine, uracil, guanine) called the start codon. The ribosome then
moves along the mRNA three bases at a time. Each group of three bases is called a
codon and corresponds to a specific amino acid. As the ribosome reads the codons on
the mRNA, the tRNA molecules with complementary bases join to the mRNA. The
sequence of three bases matching the codon is called anticodon. The amino acids
carried by the tRNA are joined so that the protein is assembled with the amino acids in
the correct seqeunce. Once the tRNA has delivered its amino acid, it detaches from the
ribosome and can then pick up another amino acid from the cytosol
Translation - Step 2 ANSWERS The ribosome then moves along the mRNA three
bases at a time. Each group of three bases is called a codon and corresponds to a
specific amino acid. As the ribosome reads the codons on the mRNA, the tRNA
molecules with complementary bases join to the mRNA. The sequence of three bases
matching the codon is called anticodon. The amino acids carried by the tRNA are joined
so that the protein is assembled with the amino acids in the correct seqeunce. Once the
tRNA has delivered its amino acid, it detaches from the ribosome and can then pick up
another amino acid from the cytosol
correct Answers
Adenine, guanine, cytosine, thymine ANSWERS Nitrogenous bases
DNA ANSWERS In the form of long strands about 2-3m long
- Consists of two strands of alternating sugar and phosphate groups with pairs or
nitrogen bases forming cross-lines between strands
Nucleotide ANSWERS Each phosphate group and sugar molecule with a nitrogen
base attached
Structure of Chromosomes - Chromosomes ANSWERS When a cell is dividing
the coiled chromatin becomes even more tightly coiled and become chromosomes
Messenger RNA ANSWERS is made in the nucleus and takes the genetic code
into the cytoplasm allowing the genetic code to be read by ribosomes
Ribosomal RNA ANSWERS makes up apporximately 60% of the mass of
ribosomes with the other 40% being protein. The rRNA ensures the correct alignment of
mRNA, tRNA and ribosome. It also has an enzymatic role in the formation of peptide
bonds between the amino acids
Mitochondrial DNA ANSWERS The organelles in the cell where the aerobic phase
of respiration occurs, releasing energy for use by the cell. It is in the form of small
circular molecules hat are not bound to proteins. There are about 5 - 10 molecules of
mtDNA in each mitochondrion. It has 37 genes all of which are essential - Nuclear DNA
is in the form of very long strands that are bound to proteins, the histones
Inheritance of mitochondrial DNA ANSWERS Normally inherited exclusively from
the mother
- The mitochondria in mammalian sperm are usually destroyed after fertilisation
Transcription - Step 1 ANSWERS Is the process by which the genetic instructions
are copied from the DNA to the mRNA molecule. The transcription is triggered by
chemical messengers that enter the nucleus from the cytosol and bind to the DNA at the
relevant gene. This causes an enzyme called RNA polymerase to being the process of
making mRNA. The helicase enzyme makes the double stranded DNA molecule come
apart. It usually seperates about 17 base pairs at a time. RNA polymerase then
transcribes the bases on one strand of the DNA to make a complementary molecule of
, mRNA. At the end of the gene, a seqeunce of bases tells the RNA polymerase to stop
copying and as a result the mRNA molecule is released. The strand that is copied is
called the template strand because it is the template from which the mRNA is made.
The other DNA strand is known as the coding strand
Transcription - Step 2 ANSWERS The helicase enzyme makes the double
stranded DNA molecule come apart. It usually seperates about 17 base pairs at a time.
RNA polymerase then transcribes the bases on one strand of the DNA to make a
complementary molecule of mRNA. At the end of the gene, a seqeunce of bases tells
the RNA polymerase to stop copying and as a result the mRNA molecule is released.
The strand that is copied is called the template strand because it is the template from
which the mRNA is made. The other DNA strand is known as the coding strand
Transcription - Step 3 ANSWERS RNA polymerase then transcribes the bases on
one strand of the DNA to make a complementary molecule of mRNA. At the end of the
gene, a seqeunce of bases tells the RNA polymerase to stop copying and as a result
the mRNA molecule is released. The strand that is copied is called the template strand
because it is the template from which the mRNA is made. The other DNA strand is
known as the coding strand
Transcription - Step 4 ANSWERS The strand that is copied is called the template
strand because it is the template from which the mRNA is made. The other DNA strand
is known as the coding strand
Translation - Step 1 ANSWERS The production of a protein using the information
that is coded into the mRNA molecule
In the cytosol, a ribosome attaches to one end of the mRNA molecule at a particular
sequence of bases (adenine, uracil, guanine) called the start codon. The ribosome then
moves along the mRNA three bases at a time. Each group of three bases is called a
codon and corresponds to a specific amino acid. As the ribosome reads the codons on
the mRNA, the tRNA molecules with complementary bases join to the mRNA. The
sequence of three bases matching the codon is called anticodon. The amino acids
carried by the tRNA are joined so that the protein is assembled with the amino acids in
the correct seqeunce. Once the tRNA has delivered its amino acid, it detaches from the
ribosome and can then pick up another amino acid from the cytosol
Translation - Step 2 ANSWERS The ribosome then moves along the mRNA three
bases at a time. Each group of three bases is called a codon and corresponds to a
specific amino acid. As the ribosome reads the codons on the mRNA, the tRNA
molecules with complementary bases join to the mRNA. The sequence of three bases
matching the codon is called anticodon. The amino acids carried by the tRNA are joined
so that the protein is assembled with the amino acids in the correct seqeunce. Once the
tRNA has delivered its amino acid, it detaches from the ribosome and can then pick up
another amino acid from the cytosol
