Mendelian Genetics Flashcards
(19 cards)
What is genotype?
Genetic information
What is phenotype?
Physical form of an organism
What determines phenotype?
Combination of genotype and environment
What does one gene code for
One gene codes for one polypeptide = one enzyme = one character
What is an allele?
An alternative form of a gene
What is a locus?
The position of a gene in the DNA of a chromosome
What are homologous chromosomes?
- Contain the same loci
- Have different alleles at the loci
What are prokaryotes?
- Asexual
- All cells are haploid
What are eukaryotes?
- Sexual
- Diploid body cells
- Haploid sex cells which join to make diploid zygotes
What happens during mitosis?
- Normal cell replacement and growth
- Diploid number of chromosomes maintained
- Parent and daughter cells identical
What happens during meiosis?
- Occurs only in sex cells
- Chromosome number halves
- Maternal and paternal chromosomes exchange information
- Daughter cells differ from parent cells and each other
What are the basic steps of meiosis?
- Chromosome replication
- Pairing of homologous chromosomes
- Crossing over
- Cell division
- No doubling
- Cell division
What are the basic steps of mitosis?
- Chromosome replication
- Chromosomes align with sister chromatids on each side
- Cell division
What are the benefits of diploidy?
- Purges mutation
- Two chromosomes with slightly different function e.g. one works best at 25C and one at 35C
What are the benefits of sex?
- Genetic variability for evolution
- Reduces competition with parents
- Protection from spread of disease
What happens during crossing over in meiosis?
- For each recombination event there is a parental and recombinant chromosome
- Genes are exchanged between paternal and maternal chromosomes
What are the consequences of meiosis?
- New combinations of parental genes due to crossing over and random assortment to daughter cells
- Haploid cells fuse with others to produce diploid zygotes
- Offspring have one random half of each parent’s genetic information
What can Mendelian Inheritance be used for?
- Paternity testing
- Disease risk assessment
- Breeding characteristics in animals
- Agriculture: disease resistance in crops
What is a monohybrid cross
- Cross two pure breeding lines
- Cross F1
- F2 have 3:1 dominant to recessive
