Flashcards in 3.7.1 Inheritance Deck (63)
What is a genotype?
The genetic make up on an organism. It describes ALL the alleles that an organism has.
What is an allele?
A different version of the same gene
What is a gene?
Short section of DNA made up of nucleotide bases, which codes for a specific order of amino acids which makes a protein.
What is a phenotype?
Observable characteristics due to environment and genetic makeup
What is a homologous pair?
A pair of chromosomes - maternal and paternal. Also known as a bivalent
What is a recessive allele?
An allele whereby you need 2 copies of it (homozygous) to express that characteristic. Its not expressed if the dominant allele is present.
What is a dominant allele?
You only need ONE copy of this allele to express this characterisitic
Homozygous dominant means?
Two dominant alleles present (in the genotype)
Homozygous recessive means?
Two recessive alleles present (in the genotype)
One recessive and one dominant allele present (in the genotype)
A codominant allele is?
Where both alleles contribute/expressed in the phenotype
What are multiple alleles?
Where you have more than two alleles for a particular gene
In a diploid organism (human) how many chromosome pairs are there?
In meiosis what happens to the diploid number?
It becomes haploid - halves
Characteristics are determined by your allele combinations, how many alleles for each characteristics end up in the gamete?
Pure breeding plants are said to be
If there are 30 boys and 15 girls what is the ratio?
Why are actual ratios not exactly the same as theoretical ratios in genetics?
Because fertilisation of gametes occurs by chance - each time a gamete is fertilised, it is an independent event of what has gone before it.
How can you try and get theoretical ratios to match observed/actual ratios?
Increase sample size so its more representative
If you were to perform a statistical test on Mendelian genetics and you where looking at observed and expected ratios - what test would you do and why?
Chi Squared - because you are comparing observed and expected values and determining if there is a statistical difference
Suppose you obtained a chi squared value of 5 and the critical value was 5.99 (2dof) - what can you conclude?
Because the chi squared value is SMALLER than the critical value - you accept the null hypothesis and there is greater than a 5% probability that the difference in the results are due to chance. There is no significant difference.
Suppose you obtained a chi squared value of 8 and the critical value was 5.99 (2dof) - what can you conclude?
Because the chi squared value is LARGER than the critical value - you reject the null hypothesis and there is less than a 5% probability that the difference in the results are due to chance. There is a significant difference.
What is the difference between monohybrid inheritance and dihybrid inheritance?
Monohybrid is the inheritance of a SINGLE gene, dihybrid is the inheritance of TWO genes (that are located on different chromosomes)
Give an examples of a characteristic that involves multiple alleles
Blood groups - IA, IB and IO
Identify the chromosomes that determine sex
Sex Chromosomes - X and Y
Female sex chromosomes are
Male Sex Chromosomes are
Which sex determines the sex of the child?
Males - as females always pass on a X in their gametes.
What are the criteria must be met to perform a chi squared test?
sample size is large (20+), data falls into catergories (green, yellow), compare experimental observations with theoretical ones (expected)