H Biology - Entire Course

What is each gene made up of?

Each gene is made up of many nucleotides

What are DNA nucleotides made up of?

DNA nucleotides are made up of;

• Deoxyribose sugar

• Phosphate

• Bases

How are DNA nucleotides joined together?

DNA nucleotides are joined together by strong bonds between the phosphate of one nucleotide and the sugar of the next.

What is the strong bond between nucleotides known as?

The strong bond between nucleotides is known as the sugar phosphate backbone of the DNA.

What are the 4 DNA bases?

The four DNA bases are;

• Adenine

• Thymine

• Guanine

• Cytosine

Which base is A?

Base A is Adenine

Which base is T?

Base T is Thymine

Which base is G?

Base G is Guanine

Which base is C?

Base C is Cytosine

Which base does adenine join with in DNA?

In DNA, adenine joins with thymine

Which base does thymine join with in DNA?

In DNA, thymine joins with adenine

Which base does guanine join with in DNA?

In DNA, guanine joins with cytosine

Which base does cytosine join with in DNA?

In DNA, cytosine joins with guanine

What kind of bonds join the complementary base pairs?

Weak hydrogen bonds join the complementary base pairs

What structure does DNA have?

DNA has a double stranded anti parallel helix structure

The 5’ end

• 5’-5 prime

• Phosphate carbon exposed

The 3’ end

• 3’-3 prime

• Sugar carbon exposed

What are the two different cell types?

The two different cell types are;

• Eukaryotes

• Prokaryotes

What feature does a eukaryotic cell have?

A eukaryotic cell has a membrane bound nucleus and organelles

What feature does a prokaryotic cell have?

A prokaryotic cell has no membrane bound nucleus and organelles

Which cells are eukaryotes?

The eukaryotic cells are;

• Plant

• Animal

• Yeast

Which cells are prokaryotes?

The prokaryotic cells are;

• Bacteria

• Archaea

What type of DNA shape do eukaryotes have within their nucleus?

Eukaryotes have linear chromosomes in the nucleus, which are tightly coiled and packaged with proteins called histones.

What DNA shape do bacterial chromosomes have?

Bacterial chromosomes have a circular chromosome shape

What DNA shape do chloroplast chromosomes have?

Chloroplast chromosomes have a circular chromosome shape

What DNA shape do mitochondria have?

Mitochondria chromosomes have a circular chromosome shape

What DNA shape do bacterial plasmids have?

Bacterial plasmids chromosomes have a circular plasmid shape

What DNA shape do yeast plasmids have?

Bacterial plasmids chromosomes have a circular plasmid shape

What is special about yeast?

Yeast is a special example of a eukaryote as it also has circular plasmids

What do prokaryotes have?

Prokaryotes have a single, circular chromosome and smaller circular plasmids

What do eukaryotes have?

Eukaryotes all have linear chromosomes in the nucleus and circular chromosomes in their mitochondria and chloroplasts

Which enzyme is DNA replicated by?

DNA is replicated by the enzyme DNA polymerase

What does DNA polymerase bind to?

DNA polymerase binds to the 3’ of each DNA strand

What does DNA polymerase add?

DNA polymerase adds DNA nucleotides to the 3’ end of the original strand

What does DNA polymerase need to start replication?

DNA polymerase needs a primer to start replication

What is a primer?

A primer is;

• A short strand of DNA nucleotides

• Binds to the 3’ end of a DNA strand

• Provides something for DNA polymerase to add nucleotides to

The leading strand

• The DNA is unwound when hydrogen bonds between bases are broken.

• DNA polymerase adds free DNA nucleotides using complementary base pairing. This goes in one direction, from 3’ to 5’

• This process is continuous.

How is DNA unwound in the leading strand?

DNA in the leading strand is unwound when hydrogen bonds between bases are broken

How does DNA polymerase add free DNA nucleotides?

DNA polymerase adds free DNA nucleotides using complementary base pairing.

Which direction does DNA polymerase add free DNA nucleotides?

DNA polymerase adds free DNA nucleotides from 3’ to 5’

What word is used to describe the process of replication on the leading strand?

The word used to describe the process of replication on the leading strand is continuous.

The lagging strand

• The lagging strand runs in the 5’ to 3’ direction, opposite to DNA polymerase action.

• The lagging strand is replicated in fragments.

• The fragments are joined together by the enzyme, ligase.

What direction does the lagging strand run in?

The lagging strand runs in the 5’ to 3’ direction, opposite to the DNA polymerase action.

What is the lagging strand replicated in?

The lagging strand is replicated in fragments.

What enzyme are the fragments in PCR joined together by?

The fragments are joined together by the enzyme, ligase.

What does PCR stand for?

PCR stands for Polymerase Chain Reaction

What is PCR?

PCR is a procedure using repeated cycles of heating and cooling to amplify target regions of DNA.

What is the first stage of PCR?

In the first stage of PCR, DNA is heated to 92°C-98°C to separate strands

What is the second stage of PCR?

In the second stage of PCR, DNA is cooled to 50°C-65°C to allow primers to bind

What is a primer?

A short strand of DNA nucleotides

Why do you need two primers for PCR?

Two primers are needed because they are complementary to target sequences at both ends of the DNA region that is to be amplified

What is the third stage of PCR?

In the third stage of PCR, DNA is heated to 70°C-80°C for heat tolerant DNA polymerase to replicate DNA region

What are three uses of PCR?

Three uses of PCR are;

• Solving crimes

• Settling paternity suits

• Diagnosing genetic disorders

Where does a primer bind to?

A primer binds to the 3’ end of a DNA strand

What does a primer provide?

A primer provides something for DNA polymerase to add nucleotides to

What can RNA be used for?

RNA can be used to synthesise proteins

What are the three RNAs?

The three RNAs are;

• mRNA

• tRNA

• rRNA

What is the translated RNA?

The translated RNA is mRNA

What are the non-translated RNAs?

The non-translated RNAs are;

• tRNA

• rRNA

What are the two types of RNA?

The two types of RNA are;

• Translated

• Non-translated

What does tRNA stand for?

tRNA stands for transfer RNA

What does rRNA stand for?

rRNA stands for ribosomal RNA

Why is mRNA called translated RNA?

mRNA is called translated RNA because the RNA is translated into a protein.

What is the structure of RNA?

The structure of RNA is single stranded

What is an RNA molecule made up of?

RNA molecules are made up of

• RNA nucleotides

• Ribose sugar

• Phosphate

What base does adenine join with in RNA?

In RNA, adenine joins with uracil

What are the RNA bases?

• Adenine

• Uracil

• Cytosine

• Guanine

What base does uracil join with in RNA?

In RNA, uracil joins with adenine

What base does guanine join with in RNA?

In RNA, guanine joins with cytosine

What base does cytosine join with in RNA?

In RNA, cytosine joins with guanine

Which base is U?

Base U is uracil

mRNA

• Carries a copy of DNA code from the nucleus to the ribosome

• Transcribed from DNA in the nucleus

• Translated into proteins by ribosomes in the cytoplasm

What is a codon?

A codon is a triplet of bases on the mRNA molecule

What does a codon do?

A codon codes for a specific amino acid

What does tRNA do?

Each tRNA molecule carries a specific amino acid to the ribosome

What does a tRNA molecule have?

• A tRNA molecule has an;

• Anti-codon

• Amino acid attachment site that is specific to one amino acid

What is an anti-codon?

An anti-codon is an exposed triplet of bases

What does rRNA do?

rRNA joins with proteins to form the structure of the ribosome

What does gene expression involve?

Gene expression involves the transcription and translation of genes

What is transcription?

Transcription is DNA to mRNA

What is translation?

Translation is mRNA to a protein

How many of the genes in a cell are expressed?

Only a fraction of the genes in a cell are expressed

How is transcription carried out?

• RNA polymerase moves along the gene unwinding the double helix and separating the strand by breaking the hydrogen bonds between the bases.

• RNA polymerase synthesises a primary transcript of mRNA from RNA nucleotides by complementary base sequence.

What are coding regions called?

Coding regions are called exons

What are non-coding regions of the primary transcript called and what happens to them?

Non-coding regions of the primary transcript are called introns and are removed

What are exons joined together to form?

Exons are joined together to form the mature transcript

What happens to the order of exons during splicing?

The order of exons is unchanged during splicing

What is tRNA involved in?

tRNA is involved in the translation of mRNA into polypeptide at a ribosome.

Where does translation begin and end?

Translation begins at a start codon and ends at a stop codon.

How do anticodons bond to codons?

Anticodons bond to codons by complementary base pairing

What does translation do?

Translation translates the genetic code into a sequence of amino acids.

How are amino acids linked?

Amino acids are linked by peptide bonds to polypeptides

What do polypeptide chains do?

Polypeptide chains fold to form the three dimensional shape of a protein.

What are polypeptide chains held together by?

Polypeptide chains are held together by;

• Hydrogen bonds

• Other interactions between individual amino acids

What do proteins have?

Proteins have a large variety of shapes which determine their function

What is an organisms phenotype?

An organisms phenotype is it’s physical characteristics.

What does the phenotype result from?

The phenotype results from the set of genes an organism possesses, the genotype

What is the phenotype determined by?

The phenotype is determined by the proteins produced as result of gene expression.

What other factor can influence phenotype?

Environmental factors can also influence phenotype.

What is DNA to mRNA called?

DNA to mRNA is called transcription