Inheritance Flashcards
Which scientist first discovered the basis of genetics?
Gregor Mendel
Which plant did Mendel use for scientific studies?
Peas
What is an allele?
A different version of the same gene
What is a gene?
A section of DNA which codes for a protein/characteristic
What is a chromosome?
A length of DNA, packaged with proteins
What is an organism’s genotype?
The alleles that the organism has
What is an organism’s phenotype?
The physical characteristics an organism has
What does it mean if an allele is dominant?
It is always expressed
What does it mean if an allele is recessive?
It is only expressed when there are two of them
How many alleles of each gene does a human have?
2; 1 from mother and 1 from father
What does it mean if a person has heterozygous alleles?
The two alleles are different
What does it mean if a person has homozygous alleles?
the two alleles are the same
How would you describe a person who had the alleles BB?
Homozygous dominant
How would you describe a person who has the alleles Bb?
Heterozygous
How would you describe a person who has the alleles bb?
Homozygous recessive
Which two alleles are used to represent biological sex?
X and Y
Is XX male or female?
Female
Is XY male or female?
Male
Which 3 alleles code for different blood groups?
A, B and O
Which blood group allele is recessive?
O
What does it mean if genes are codominant?
Two dominant genes are expressed simultaneously. E.g. in blood groups, A and B can both be expressed (Blood type AB)
Alleles for sex-linked disorders are usually located on which chromosome?
X
Why are males more likely to suffer from a sex-linked disorder?
Sex-linked disorders are caused by recessive alleles on the X chromosome. Females have two X chromosomes so would need to inherit the allele from both parents. Males only have 1 chromosome so inherit the allele from their mother.
What causes genetic variation?
mutations and random sorting of chromosomes during meiosis and sexual reproduction
What is a mutation?
A change in DNA sequence
What causes environmental variation?
Differences in environment
Are all mutations negative?
No. Some can be beneficial (e.g. antibiotic resistance in bacteria), some will have no effect and some will cause a change which is neither positive or negative (e.g. different eye colours)
