DNA & Genes
The molecule that stores genetic information.
DNA
The coding region of a DNA strand
Gene
The entire genetic makeup of an organism is its _____.
genome
A change in DNA that can cause a genetic disease is called a _____.
Mutation
A treatment that aims to correct or replace a faulty gene is called _____.
Gene therapy
Name at least two components of a DNA molecule
Nitrogenous Base
Phosphate Group
Deoxyribose Sugar
Different versions of the same gene are called these.
Allele
An allele that is expressed when only one copy is present is _____.
Dominant
This genetic disease causes abnormal haemoglobin and crescent moon-shaped red blood cells.
Sickle Cell Anaemia
Name at least two ways to treat genetic diseases at the gene level
Gene silencing
Gene replacement
Gene editing
Fully name the four nitrogenous bases found in DNA.
Adenine, thymine, cytosine, guanine
An organism with two identical alleles for a gene is _____.
Homozygous
If T = tall and t = short, what percentage of offspring would be tall from Tt × Tt?
75%
The main symptoms of Cystic fibrosis
excessive sticky mucus production that blocks airways and pathways
This technology can make a targeted change to a specific DNA sequence.
CRISPR
Which bases are complementary to each other? And what type of bond joins them?
A with T
G with C
Hydrogen Bonds
A mutation changes a DNA codon from GAA → GAG, What type of mutation is this?
Substitution
Two parents are both carriers for a recessive disease. What is the probability their child will be affected?
25%
Why are recessive genetic diseases sometimes carried by people who show no symptoms?
They possess one recessive disease allele but a second functional dominant allele prevents the disease phenotype
Why can gene therapy be difficult to use as a treatment for genetic diseases, even if scientists know which gene is faulty?
The therapeutic gene must be delivered into the correct cells and expressed correctly. It can also be difficult to deliver the gene to enough cells, and the treatment may cause immune responses or unintended effects.
How is DNA stored in a human cell.
The most detailed answer gets the points
- in the nucleus
- condensed as chromosomes
- 46/23 pairs
- Every cell (except red blood cells)
Explain why a mutation in a gene can sometimes have no effect on an organism's phenotype.
The mutation may be in a non-coding region, may be a silent mutation, or may not significantly alter protein function
What advantage do females have compared with males when inheriting a recessive genetic disease located on the X chromosome?
Females have two X chromosomes, so they have a second copy of the gene. If one X chromosome carries a recessive disease allele, a normal allele on the other X chromosome may mask it, meaning the female may be an unaffected carrier rather than having the disease.
Explain why a mutation in a tumour-suppressor gene could increase the risk of cancer.
Tumour-suppressor genes normally help prevent uncontrolled cell division; loss of their function can allow abnormal cells to proliferate
Compare gene replacement, gene editing and gene silencing as approaches to treating genetic disease.
Gene replacement: adds a functional copy of a gene. Gene editing: directly changes the faulty DNA sequence. Gene silencing: reduces or stops expression of a harmful gene.