DNA and genetics Flashcards
what is DNA?
a single long molecule that contains the genetic code of living things
how is DNA stored?
-Dna has to be coiled tightly into the nucleus
-the nucelus is made when dna is wraped around called histones
-nucleus densley folds over one another to be compact in size
-chromatin continues to folds layer over layer until entire dna molecule is condensed into a single chromosome
main function of dna
direct growth -dna and development of organisms
what is incomplete dominance
-neither allele will be expressed fully in a heterozygous genotype
what are homologous chromosomes?
-two chromasomes inside nucleus that have the same length and gene sequence
what is a karyotype
- genetic screening of arranged chromasomes from shortest to longest
what can be found on the structure of a chromasome?
-on a chromaosme there are diffrent bands. each band is a specific gene
-each gene is found on a specififc locus.
-each gene has diffreent forms called alleles
what are erros in meiosis called and what are they?
-called non-disjunction
- inncorrect seperation in a chromosome during gamete production
who was Greger Vendel
-conducted experiment on pea plants studying specifc genetic trait inhertiation
what is a genotype?
- a combination of alleles to make a trait
what is a phenotype?
- an observable trait
how are identicial twins produced?
- one mature egg is fertalized by sperm and the zygote divides into two identical cells by mitosis
- the offspring will be male or female
how are fraternal twins produced?
-two mature eggs are released and fertalized by different sperm cells
-two seperate zygotes are developed
-the offspring can be different sex
what are some autosomal recessive diseases?
-cystic fibrosis
-sickle cell anemia
what is a homozygous genotype
same allele
what is a heterozygous allele?
- a genotype of different alleles
how many cells are produced at the end of spermatogenesis ?
4 haploid cells
how many cells are produced at the end of oogenesis
- one
explain the process of meosis 1
- interphase
-each of the homologous chromasomes duplicates into their own sister chromatids
-prophase 1
2 centrioles move to the opposite ends and release spindle fibers then homologous vhromsomes pair up by synapsis anf their chromatids exchange genetic info - Metaphase
the homologous pair line up in the middle of the cell and attach to spndle fibers by their centromere
-Anaphase
homolous pais are pulled apart and go to opposite sides
-Telophase
the chromassomes travel away to opposite ends
what is codominance?
where both alleles are expressed, none of them are dominaant over the other
