genetics Flashcards
define genetics
biology dealing with the study of genes, genetics, variation and heredity in organism
what is genetics commonly know as?
the study of how traits are passed on
what is a gene?
a gene is a basic unit of heredity that is located on the nucleus and is made up of DNA, and codes for specific protein
how is chromosome formed?
-the DNA wraps around histone proteins
-8 histone proteins wrapped around the DNA makes up the nucleosome
-the nucleosome condenses to form chromatin fibers
-the chromatin fibers fibers condense to form chromosome
define allele
different versions of the same gene where each allele comes from one parent
define locus
specific position on a chromosome, where a particular gene is found
what is a trait?
physical or behavioral characteristic that is passed on and is determined by genes
what is a homologous chromosome?
pair of chromosome which is similar in shape, locus, centromere and chromosomal length but different versions of genes
what is a heterozygous allele?
allele which has different version of the same gene
what is a homozygous allele?
alleles which are the same version of the gene
what is a dominant allele?
allele which suppresses expression of the alternate allele
what is a recessive allele?
an allele that is masked by the dominant allele
where can traits appear in dominant allele?
in heterozygous-Bb
in homozygous-BB
where can traits appear in recessive allele?
only in homozygous-bb
what is a genotype?
genetic makeup of an organism
what is a phenotype?
observable characteristic resulting from genotypes interaction with the environment
what did George Mendel do?
looked at seven traits of pea plants
seed-pod-stem-flower
what is a monohybrid cross?
a genetic cross involving single pair of gene
eg: TT and tt
define incomplete dominance
one allele is not completely dominant over the other so they blend
define codominance
both alleles are expressed fully and separately
what is a sex-linked trait
diseases that are caused due to the X chromosome carrying the recessive defective gene and therefore men are more susceptible to certain diseases
what are the common disease in sex-linked traits?
1-colorblindess
2-hemphilia;blood cannot clot
what are Mendel’s theory
1-dominance
2- segregation
3-independant assortment
describe the dominance law
when pure parents with different traits of a particular gene are crossed, only the dominant trait will be passed on to the offspring
describe the law of segregation
each gamete gets one allele for a particular gene
describe the law of independent assortment
the allele of particular gene given to offspring is random and not dependent on another allele of a gene
