DNA and genetics

Question 1

what is DNA?

Answer 1

a single long molecule that contains the genetic code of living things

Question 2

how is DNA stored?

Answer 2

-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

Question 3

main function of dna

Answer 3

direct growth -dna and development of organisms

Question 4

what is incomplete dominance

Answer 4

-neither allele will be expressed fully in a heterozygous genotype

Question 5

what are homologous chromosomes?

Answer 5

-two chromasomes inside nucleus that have the same length and gene sequence

Question 6

what is a karyotype

Answer 6

• genetic screening of arranged chromasomes from shortest to longest

Question 7

what can be found on the structure of a chromasome?

Answer 7

-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

Question 8

what are erros in meiosis called and what are they?

Answer 8

-called non-disjunction
- inncorrect seperation in a chromosome during gamete production

Question 9

who was Greger Vendel

Answer 9

-conducted experiment on pea plants studying specifc genetic trait inhertiation

Question 10

what is a genotype?

Answer 10

• a combination of alleles to make a trait

Question 11

what is a phenotype?

Answer 11

• an observable trait

Question 12

how are identicial twins produced?

Answer 12

• one mature egg is fertalized by sperm and the zygote divides into two identical cells by mitosis
• the offspring will be male or female

Question 13

how are fraternal twins produced?

Answer 13

-two mature eggs are released and fertalized by different sperm cells
-two seperate zygotes are developed
-the offspring can be different sex

Question 14

what are some autosomal recessive diseases?

Answer 14

-cystic fibrosis
-sickle cell anemia

Question 15

what is a homozygous genotype

Answer 15

same allele

Question 16

what is a heterozygous allele?

Answer 16

• a genotype of different alleles

Question 17

how many cells are produced at the end of spermatogenesis ?

Answer 17

4 haploid cells

Question 18

how many cells are produced at the end of oogenesis

Answer 18

• one

Question 19

explain the process of meosis 1

Answer 19

• 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

Question 21

what is codominance?

Answer 21

where both alleles are expressed, none of them are dominaant over the other