1) Genetics Flashcards
what kind of cells does meiosis produce?
- diploid cells
- 23 chromosomes
what happens in meiosis?
- chromosome replicates
- chromosomes stay attached
- they pair up
- then separate into two new cells
- produces 4 haploid daughter cells
why are the cells different?
-different versions of the same genes
what is a zygote?
single fertilised egg cell
what is the structure of DNA?
- two strands in helix shape
- joined together by bases
- to make a double helix
what are the 4 bases and what are their pairs?
what kind of bone do they have?
- adenine, thymine, cytosine, guanine
- T and C
- A and G
- weak hydrogen bond
what is a genome?
- all the DNA in an organism
- each cell contains a copy of the genome
what is a gene and its role?
- section of DNA in a chromosome
- coded instructions which allow scientists to see your DNA
how can DNA be extracted from fruit?
- dissolve 3g of salt in 100cm3 of water. add 10cm3 of washing up liquid. stir.
- mash 50g of peas and add to the solution. stir.
- water bath(60degrees) for 15 min
- filter the mixture
- 10cm3 of filtrate into a testube
- two drops of protest enzyme solution
- add ice Cold ethanol
- white layer of DNA should form
why is there differences in inherited characteristics?
- contain slightly different instructions
- create variations
- different forms of the same gene are alleles
what is a chromosome?
- found in nuclei
- contain DNA
what is a gene?
-section of DNA in a chromosome
what is allele?
-different forms of the same gene
what is dominant?
- allele always affects phenotype
- opposite to recessive alleles
what is recessive?
-allele that will only affect phenotype if other alleles are recessive
what is heterozygous?
-if the alleles are different in the gene
what is homozygous?
-if both alleles of the same gene are the same
what is a gamete?
- only one copy of each chromosome
- one copy of each gene
what is zygote?
-fertilised egg
what is monohybrid inheritance? How can it be shown/explained?
- inheritance of one gene
- shown using Punnett squares and Family Predigrees
what are sex chromosomes and which do male and females have?
- two chromosomes decide what sex you are
- females- X
- male- X and Y
which sex chromosome is more dominant and decides what sex you will be?
-male Y
how can pungent squares be used to determine your sex?
- boxes show possible genotypes
- two contain XX
- two contain XY
- ratio= 2:2
- equal chance of a boy or girl
what does a family pedigree chart show?
-shows hoe genotypes + phenotypes are inherited
