DNA and RNA Flashcards
What is heredity?
Characteristics passed on from parents to offspring in the form of genes
Example: Passing on of brown hair
Define gene.
A section of DNA that codes for a particular protein
What is gene expression?
A gene is expressed in the organism’s phenotype
How does gene expression manifest in phenotype?
E.g. a person has an allele for blue eyes but expresses brown eyes due to dominance
Define chromosome.
A structure composed of DNA and protein
What is the composition of chromosomes?
- 60% protein
- 40% DNA
How many pairs of chromosomes do humans have?
23 pairs
What is junk DNA?
DNA that does not code for a protein, also known as non-coding DNA
What percentage of DNA is considered junk DNA?
97%
Define exons.
Coding DNA in genes
Define introns.
Non-coding DNA in genes that fills the gaps between exons
What is the genetic code?
A sequence of bases in DNA that instructs the cell to produce a specific protein
What is a triplet/codon?
A sequence of 3 bases that code for a specific amino acid
Name the three types of codons.
- Start codon
- Stop codon
- Amino acid codon
What does DNA stand for?
Deoxyribonucleic acid
What does RNA stand for?
Ribonucleic acid
What is DNA profiling?
The way in which DNA is analysed to find a matching sample
What is DNA extraction?
DNA is taken out from the cell as the cell is broken down
What is DNA cutting?
DNA is cut into different sized fragments using restriction enzymes
What do restriction enzymes do?
Cut DNA at particular combinations of nucleotides
What is electrophoresis?
The process of separating DNA fragments on the basis of length using an electric current in a gel
How does the size of DNA fragments affect their movement in gel electrophoresis?
Bigger cut pieces take longer to move and separate out in the gel
What happens during DNA transfer?
DNA is transferred from gel to filter paper
What is the purpose of analysis in DNA profiling?
To compare the pattern of bands of DNA formed to find a match
List applications of DNA profiling.
- Forensic science (crime scene analysis)
- Paternity tests
What is genetic screening?
Testing of a sample for the presence of a particular gene (or variant)
What can genetic screening help diagnose?
Genetic diseases
Who discovered the structure of DNA?
Watson and Crick
What is the structure of DNA?
A double helix structure - 2 strands of DNA joined together in a spiral shape
What is RNA composed of?
Nucleotides
Each nucleotide has a 5 carbon sugar (deoxyribose), a phosphate, and a nitrogenous base.
What are the two types of nitrogenous bases in RNA?
Purines and pyrimidines
Purines include Guanine and Adenine; pyrimidines include Cytosine and Thymine.
What is the structure of RNA?
Single strand
RNA is composed of nucleotides with ribose sugar.
Which nitrogenous base in RNA replaces Thymine?
Uracil
In RNA, Adenine joins with Uracil instead of Thymine.
What is mRNA?
Messenger RNA
Carries information to code for a protein from DNA in the nucleus to ribosomes in the cytoplasm.
What is tRNA?
Transfer RNA
It carries amino acids in the cytoplasm to the ribosomes and contains anticodons complementary to mRNA codons.
What role does rRNA serve?
Ribosomal RNA
Forms part of the ribosome structure and helps match codons on mRNA with the appropriate amino acids.
What are codons?
Sequences of three nucleotides
Each codon corresponds to a specific amino acid.
Fill in the blank: The bases in RNA join to each other using _______.
Hydrogen bonds
True or False: Adenine pairs with Thymine in RNA.
False
In RNA, Adenine pairs with Uracil.
List the components of a nucleotide.
- 5 carbon sugar (ribose)
- Phosphate
- Nitrogenous base
What base does DNA contain?
Thymine (T)
DNA contains four bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
What is the structure of DNA?
Double stranded (double helix)
The double helix structure of DNA was first described by James Watson and Francis Crick.
Where is DNA found in the cell?
Nucleus
DNA is primarily located in the nucleus, but some DNA can also be found in mitochondria.
Where does DNA replication take place?
In the nucleus
DNA replication is a crucial process that occurs before cell division.
What base does RNA contain that DNA does not?
Uracil (U)
In RNA, uracil replaces thymine found in DNA.
What is the structure of RNA?
Single stranded (single helix)
RNA molecules are typically single-stranded and can fold into complex shapes.
What occurs during transcription?
A sequence of bases on DNA are copied to mRNA
Transcription is the first step in gene expression, synthesizing mRNA from DNA.
What does RNA polymerase do?
Forms an mRNA strand
RNA polymerase catalyzes the transcription of RNA from a DNA template.
What are codons?
Triplets of nucleotides on mRNA
Codons specify which amino acid will be added during protein synthesis.
What types of codons are formed?
- Start
- Stop
- Amino acid
Start codons signal the beginning of translation, while stop codons signal termination.
What is the significance of DNA replication?
DNA can make exact copies of itself that can be passed on to each new generation of cells
This process is essential for growth, repair, and reproduction.
What happens during translation?
A sequence of bases on mRNA is used to create a sequence of amino acids
Translation occurs in the ribosome and is the second step of gene expression.
Where does mRNA move after transcription?
To the cytoplasm
Once mRNA is synthesized, it exits the nucleus and enters the cytoplasm for translation.
What role does tRNA play in translation?
Carries an anticodon which is complementary to a codon on mRNA
tRNA molecules bring the appropriate amino acids to the ribosome during protein synthesis.
What does each tRNA molecule carry?
A specific amino acid
The amino acids carried by tRNA are linked together to form proteins.
True or False: DNA replication results in identical double strands.
True
Each new DNA molecule consists of one original and one new strand.
What does tRNA bring to the mRNA codon?
An amino acid
What happens to amino acids from the tRNA during protein synthesis?
They detach and bond together, forming a chain of amino acids
What role does tRNA play in the ribosome?
Pulls the mRNA through the ribosome
What is formed from the chain of amino acids after folding?
A functional protein
What is the first step to isolate DNA from plant tissue?
Chop up the onion
What is added to the onion to clump the DNA?
Salt
What is the purpose of adding washing-up liquid to the onion?
Breaks down the cell membrane and releases DNA
At what temperature and for how long should the beaker be placed in a water bath to denature enzymes?
60 degrees for 15 mins
What is the purpose of cooling the beaker in ice?
Stops any further breakdown of the DNA
How long should the mixture be blended to release DNA?
3 seconds
What type of filter is used to filter the mixture?
Coffee filter paper
What does protease do in the DNA isolation process?
Breaks down the proteins that surround the DNA
What is added to the test tube to make the DNA precipitate out of solution?
Ice cold ethanol
What is observed when twisting a glass rod in the test tube?
White stringy DNA strands are present
Fill in the blank: tRNA brings an _______ to the necessary mRNA codon.
amino acid
True or False: Blending the mixture for a longer period will not damage the DNA.
False
