Genes & Genome Flashcards
Define Genome
All the DNA of an organism
Since when do humans have their genome?
Since fertilisation
What are the three main types of DNA?
Nuclear DNA, mitochondrial DNA, and Chloroplast DNA
What are possible traits of nucleotide sequences?
They are genes
Regulatory (on/off)
Non-coding (Introns)
Tandem Repeats (repetitive)
What is a Gene?
A heritable factor that consists of DNA and influences specific characteristics
OR
A sequence of DNA nucleotides that codes for a RNA or protein product
Define Locus
A specific location on a chromosome where a gene is located
OR
A specific location on a gene
Define allele
A different variation of the same gene
Give an example of an alelle
A gene encodes for the eye Color brown, dependent on the parents, the alternative code may be for blue eyes
How are new alleles formed?
Through mutations
What is a chromosome
Supercooled DNA and associated structural proteins
What is chromatin
A string of DNA wrapped around histone proteins
What is Gene expression
The process by which a gene creates a product
When is the X shape of a chromosome seen?
Only seen in prophase and metaphase when a cell has replicated its DNA and is dividing.
What does a chromosome look like when its not dividing?
Like one leg of a chromosome pair
Letters for homozygous dominant
AA
Letters for heterozygous
Aa
Letters for homozygous recessive
Aa
How are alleles of the same gene the same?
They are the same gene and both code for the same type of protein(eg hair Color). They occupy the same locus on homologous (similar) chromosomes and the majority of the sequence remains the same between alleles.
How do alleles differ from one another?
They base sequence is slightly different
Which gene and corresponding protein is cystic fibroses controlled by?
The CFTR gene and Chloride ion channel protein
What mutation is sickle cell disease caused by?
Mutation in the hemoglobin-beta gene
What does a RBC experiencing sickle cell disease look like?
Like a half moon
Why did the hemoglobin-beta gene mutate?
First it was an adaption to malaria (so that the virus cannot sit on the RBC).
What is the issue with sickle cell anemia?
Oxygen cannot sit well on the half moon RBC, the life span of RBC is shorter so they die quicker and clotting occurs at a much higher rate.
How many copies of chromosomes do eukaryotes have?
At least two. Meaning individuals have two alleles that may be the same or different
What are mutations?
Changes to the base pair sequence of the organisms genetic code
What is a germline cell?
One that gives rise to gametes(eg. egg or sperm cells)
What happens when a mutation occurs in a germline cell?
The mutation can be passed on to offspring
What is a body cell called?
Somatic
What happens when a mutation occurs in a somatic cell?
Mutations are passed on to daughter cells during mitosis but are not passed on to offspring. An example includes cancer.
Describe a spontaneous mutation.
A mutation that arises naturally and not as a result of exposure to mutagens.
They occur due to errors in DNA replication
List a few examples of mutagens
UV light
Radiation(hiroshima)
Cigarettes
Radioactive substances
X-Rays
What is the cause of physical mutation
Exposure to radiation that damages the DNA
What is the cause of chemical mutation
exposure to chemicals (eg. heavy metal ions) that damage the DNA
What is biological mutation?
Viruses that insert themselves into host DNA
When did Hiroshima happen?
1945
What was hiroshima
the US detonated two atomic bombs over Japan. Between 100,000-200,000 thousand people died. Many thousands died prematurely over the years due to radiation-induced cancer/ mutations in DNA. Second-generation bomb victims experience mutations.
When did Chernobyl happen?
1986
What is silent mutation?
There is no change to the polypeptide sequence
What was Chernobyl?
Due to a flawed reactor design of not properly trained personnel. The plant released many radioactive isotopes into the atmosphere, polluting over 200,000 km^2. Instant effects were dizziness, fatigue, and vomiting. Long-term physiological consequences affected antioxidants, hormones and immunity. Long-term physical effects were leukaemia and cardiovascular diseases.
What is missense mutation?
A single amino acid is changed
What is nonsense mutation?
A stop codon is created, polypeptide sequence is stunted
Explain why a horse(64 chr. pairs) and a donkey(62. chr. pairs) have offspring with 63 pairs? And what does this mean?
Because the left over chromosomes pair up. This number is uneven so the offspring is infertile.
How is DNA structured/ organized?
With nucleoide arrangement, phosphate, pentose sugar, base. The shape is a helix
What is the uncoiled structure of a chromosome?
A single double-stranded helix.
When are chromosomes homologous pairs?
When maternal and paterna; chromosomes align during fertilization
