B5.1 Inheritance Flashcards
What is a gamete?
A gamete are sex cells (sperm or eggs)
What is a chromosome?
Tightly packaged DNA around histone proteins
What is a gene?
A section of DNA that can (but not always) code for a protein
What is an allele?
Different versions of the same gene
What is a dominant allele?
A version of a gene where only one copy is needed for it to be expressed
What is a recessive allele?
A version of a gene where two copies are needed for it to be expressed
What is meant when an organism is homozygous?
When an organism has two copies of the same allele (two recessive or two dominant)
What is meant when an organism is heterozygous?
When an organism has two different versions of the same gene (one dominant and one recessive)
What is the genotype?
The genes present for a trait
What is the phenotype?
The visible characteristic
What is the genome?
All of the genes present in an organism
What is discontinuous variation?
Variation that produces distinct categories (e.g. eye colour or blood groups)
What is continuous variation?
Variation that cannot be placed into distinct categories and instead produces a spectrum (e.g. height, weight)
What causes variation?
Mutations in the genetic code
Describe how a mutation in a coding DNA sequence could be detrimental (Higher)
- The mutation may change the sequence of amino acids in the protein which will change its structure
- This may affect the protein, particularly in specific molecules like enzymes and antibodies
What may happen if there is a mutation in non coding DNA? (Higher)
It may stop transcription and alter the expression of genes
Give one advantage and one disadvantage of sexual reproduction
Advantage - It introduces variation
Disadvantage - It is slower and produces a limited amount of offspring
Give one advantage and one disadvantage of asexual reproduction
Advantage - It produces lots of offspring quickly
Disadvantage - It does not introduce variation and so all offspring are susceptible to the same environmental pressures as the parents
What is the difference between diploid and haploid cells?
- Haploid cells have half the amount of genetic information as diploid cells
- Haploid cells are germ cells
- Diploid cells are body cells
What type of cell does meiosis produce?
Haploid germ cells (sperm and egg cells)
How are dominant alleles represented in a punnett square?
They are represented using uppercase letters
How are recessive alleles represented in a punnett square?
- They use the lowercase version of the same letter as the dominant allele
Give 3 important findings of Gregor Mendel
- Organisms inherit hereditary units from their parents
- Offspring receive units from both parents and so share traits with both parents
- Traits can be passed on but not visible
What discovery lead to people accepting Mendel’s ideas?
The discovery of the gene
