Genetics Flashcards
What is DNA
Comprised of of base pairs of nucleotides bound together by hydrogen bonds to create a double helix
What are the four base pairs
Adenine with thymine
Guanine with cytosine
What is transcription
this is the process of making mRNA
What is step 1 in this mRNA process.Each gene is individually transcribed
step 1 - Beginning: Every gene contains a promoter that signals the start of the gene at the 5’ end. This is the starting place for the DNA’s separation.
Step 2
Elongation - RNA polymerase uses one of the DNA strands as a template to create an RNA strand.
Step 3
Termination - The RNA copy is finished and released from the RNA polymerase once the terminator DNA sequence is reached.
What happens at the end of a 5’ end of a chain
The phosphate group of the chain’s first nucleotide sticks out at the 5’ end. This is referred to as the 5’ end of the sugar ring because the phosphate group is connected to its 5’ carbon.
What happens at the end of a 3’ chain
The hydroxyl of the final nucleotide added to the chain is visible at the other end, known as the 3’ end. This is referred to as the 3’ end of the sugar ring because the hydroxyl group is joined to the 3’ carbon.
What is genes
Gene shows on double helix in sections you get larger and smaller which the first expressed gene forms a protein
What is protein coding
mRNA is converted into proteins via translation
What happens in translation
During translation groups of three mRNA nucleotides (a codon) equate to one amino acid.There are 64 possible codons and 20 possible amino acids.Three codons cause protein synthesis to stop
What happens if there is a mutation
Can cause incorrect amino acids or premature termination of the polypeptide chain
What is proteins and there functions
As specified in the DNA code, proteins are polypeptides made of a chain of amino acids.
The great majority of biological activities are performed by proteins, which fold into three-dimensional structures to perform specialised tasks.
What are the three types of mutation
Substitutions and Deletions and Insertion
Why does a mutations occur
Mutations in the DNA sequence are likely to result in a change in the protein output of a gene and are the root cause of genetic disease.
What is point mutations
Missense mutations- Sickle cell anaemia
Nonsense mutations- Many cancers
What is Frameshift mutations
Insertion mutations- Fragile X syndrome
Deletion mutations- Prader-Willi syndrome
What are Chromosomes
Are coiled up portions of DNA.
22 pairs of autosomes
2 allowsomes (sex chromosome)
XX female
XY male
What is Mitosis
Produces two genetically identical daughter cells
Accepted as being comprised of five stages
Prophase
Metaphase
Anophase
Telophase
Cytokinesis
What is Trisomy 21 - Down Syndrome
Three copies of chromosomes 21 (additional chromosmes)
Non Invasive Prenatal Testing blood test can be done for when a woman receives a higher chance result forT21
Trisomy 13 - Patau Syndrome
Caused by an additional copy of chromosome 13 - but the copy is only present in some of the baby’s cells - mosaic
in partial form Patau’s syndrome, the baby has only inherited part of an extra copy of chromosome 13
Incidence 1 in 10,000 live births.Average survival age 2 ½ days
Trisomy 18 - Edwards Syndrome
disorder in which babies are born with 3 copies of chromosome 18 instead of 2.Rate of occurrence Less than 10% of live babies survive the first year, with 95% of them dying in utero.
Turners syndrome (XO)
condition that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing. Turner syndrome can cause a variety of medical and developmental problems, including short height, failure of the ovaries to develop and heart defects.
What is Mendelian Inheritance
Law of segregation
Law of independent assortment
Law of dominance
What is Law of segregation
a trait relies on two alleales, one from each parent
What is Law of independent assortment
Genes for different traits can segregate independently during the formation of gametes
What is Law of dominance
Some alleles are dominant while others are recessive; an organism with at least one dominant allele will display the effect of the dominant allele.
What is punnett square
Used to predict a specific phenotype in offspring
Require knowledge of both biological parents’ genotypes
Four possible outcomes, each with a 25% probability
Squares may be the same, making the probability of this outcome cumulative
What is Huntingtons disease
Fatal condition causing the breakdown of nerve cells in the brain.
