Chapter 3

Question 1

DNA

Answer 1

Traits coded by Genes => on chromosomes => made of DNA (discovered by Crick + Watson, humans + chimps share 99% of DNA)
(DNA->chromosomes->genes->Genome!

Question 2

Prokaryotes!

Answer 2

3.5 byo
Single-Celled bacteria
No nucleus or organelles (a cell wall aorund disorganized DNA)

Question 3

Eukaryotes!

Answer 3

1.2 byo
Some single-celled, all multi-cellular organisms (humans!)
DNA in nucleus, has organelles (mitochondria)

Question 4

Somatic cells

Answer 4

Body cells (brain, blood, bone, skin)
Have full set of DNA (46 chromosomes)
Mitosis (my toes! Split + creating two copies)

Question 5

Gametes

Answer 5

Sex cells
Eggs (ova) + sperm
Half DNA (23 chromosomes)
Meiosis (split + only half of DNA)

Question 6

Chromosomes

Answer 6

DNA packaged in chromosomes

Chromosome # varies by species, are same size and arrange in pairs

Question 7

DNA structure - DOUBLE HELIX!

Answer 7

sugar + phosphate = “sides” of ladder (outside)
Nucleotide base =
Adenine + Thymine
Guanine + Cytosine

Question 8

Chromosome types

Answer 8

A set = karyotype
Homologous pairs 
-autosome (22 pairs)
-sex chromosome (1 pair) - X+Y
male determines sex

Question 9

MITOSIS (my toes…hihi)

Answer 9

Diploid
chromosomes replicated = c have same karyotype = switching process that turns on specific c (2 separate entities, 46 becomes 46)

Question 10

MEIOSIS

Answer 10

Haploid: 23 chromosomes (no pairs)
Recombination via crossing over (haplotypes)
Mitosis => then replicate again

Question 11

Law of Independent Assortment

Answer 11

Mendel’s peas- Inheritance of one trait does not affect inheritance of other traits.

Question 12

Protein synthesis

Answer 12

DNA codes for proteins = Enzymes catalyze chemical reactions. Ie. Lactase! Folks who aren’t lactose intolerant are mutants!
Structural proteins = tissues (collagen, skin + bone)
Gas transport (to tissues)
Antibodies ( immune syst.)
Hormones (regulate metabolism)
Mechanical proteins (actine+myosine)
Nutrients

Question 13

Transcription

Answer 13

DNA transcribed into mRNA in the nucleus of the cell

Transcription - translation - replication

Question 14

Translation

Answer 14

mRNA (messengerRNA) translated into an amino acid chain at the ribosomes
(Transcription - translation - replication)

Question 15

Regulatory Genes

Answer 15

On/off switches for genes•
Marfan syndrome• (BIG HANDS)
Chicken teeth•
Human hair•
Lactose intolerance or persistence!!!!! MUTANTS!!!!

Question 16

Polymorphisms

Answer 16

Variations in specific gene. Presence of 2 or more alleles at a locus.

Question 17

Law of segregation

Answer 17

2 alleles for any given gene (or trait) are inherited, one from each parent; during gamete production, one of the two alleles will be present in each ovum or sperm.

Question 18

Homeotic genes (Hox)

Answer 18

Regulatory genes responsible for form + arrangement of tissues.

Question 19

Codominance

Answer 19

2 diff. alleles that are equally dominant, both are expressed in phenotype.

Question 20

Polygenic traits + pleiotropy

Answer 20

Many traits are polygenic
(multiple genes)
Many genes are pleiotropic (influencing diff. phenotypes)
ALL TRAITS product of genes + env.

Question 21

Phenotype vs. Genotype

Answer 21

Expressed outwardly (expression of genotype) vs. expressed genetically (combination of alleles)

Question 22

Epigenetics

Answer 22

chemical changes genome affecting how DNA is used in production of proteins, without altering the DNA sequence.•Environmental change

Question 23

Methylation

Answer 23

Attachment of methyl group to DNA; affects gene expression.

impact env. on foetus

Question 24

Polygenic Inheritance

Answer 24

Continuous traits governed by alleles at two or more loci. Phenotypal.

Question 25

Mitochondrial Inheritance

Answer 25

powerpacks of c, has own DNA, mtDNA is matriarchal, only changes with mutations)