Protein synthesis and selection

Question 1

eukaryotic vs prokaryotic DNA

Answer 1

Linear: Circular
Associated with histones: Not associated with histones
Contains introns: doesn’t

Question 2

definition of a gene

Answer 2

sequence of DNA that codes for the amino acid sequence of a polypeptide

Question 3

contrasting and comparing DNA and mRNA

Answer 3

Both: Polymers made from nucleotides
linked by phosphodiester bond

Contrast
Double stranded: single stranded
Longer:shorter
Thymine:uracil
Dexyribose:ribose
Hydrogen bonds: no hydrogen bonds
Introns: no introns

Question 4

tRNA

Answer 4

Amino acid binding site, anticodon binding site, hydrogen bonds between complementary bases- sugar phosphate backbone

Question 5

genome definition

Answer 5

complete base sequence of all DNA found within a cell

Question 6

chromosome definition

Answer 6

single molecule of DNA which contains some of the genetic material of an organism

Question 7

locus definition

Answer 7

fixed position of a gene on a chromosome

Question 8

histone

Answer 8

a protein that linear DNA coils around to form a DNA- histone complex

Question 9

proteome

Answer 9

full range of proteins that a cell is able to produce

Question 10

Where does transcription occur

Answer 10

prokaryotes: Cytoplasm
Eukaryotes: Nucleus

Question 11

Introns definition vs exon definition

Answer 11

introns- non-coding sequence with a gene of DNA
Exon- coding sequence within a gene of DNA

Question 12

Describe the process of transcription

Answer 12

DNA helicase breaks hydrogen bonds between complementary bases
only one strand acts as a template
RNA nucleotide attracted to exposed bases
Adenine- uracil
cytosine-guanine
RNA polymerase joins RNA nucleotides together forming phosphodiester bond through condensation reaction
pre-mrna spliced to remove introns

Question 13

describe the process of translation

Answer 13

mRNA binds to ribosome
ribosome finds the start codon
trna with complementary anticodons bind to codon
catalyzes the formation of a peptide bond between amino acids using energy from ATP
tRNA released as ribosome moves along
ribosome releases polypeptide into RER when stop codon is reached

Question 14

Universal definition

Answer 14

the same three bases on mRNA code for the same three amino acids in all organisms

Question 15

non-overlapping definition

Answer 15

each base is read once in a triplet

Question 16

degenerate definition

Answer 16

more than one triplet for each amino acid

Question 17

mutations

Answer 17

gene mutation is a change in the base sequence that may change primary structure of a polypeptide. Ultimately leading to the change of the tertiary structure making the shape of the active site not complementary to the substrate

Question 18

types of mutations

Answer 18

substitution- in third base will not alter the amino acid coded for. in second base will be a silent mutation, in first base will change amino acid base sequence

addition/deletion
1 full DNA nucleotide is lost- results in an alteration of base triplet

Question 19

mutagenic agents

Answer 19

High energy ionization energy- alter DNA structure by interfering with DNA replication
DNA reactive chemicals- nitrous acid can remove NH2 group from cytosine converting base to Uracil
Biological agents such as some viruses and bacteria

Question 20

Chromosomal mutations

Answer 20

inversion-when a segment of bases is reversed end to end
duplication- doubling part of a chromosome
translocation- when groups of base pairs relocate from one area of the genome to another- usually between non-homologous chromosomes

Question 21

allele definition

Answer 21

different version of the same gene

Question 22

Phenotype vs genotype

Answer 22

an organisms characteristics, phenotype, is determined by the genotype and its interaction with the environment

Question 23

gene pool/ genetic diversity

Answer 23

the number of differnt alleles of genes in a population

Question 24

natural selection definition

Answer 24

process by which organisms that are better adapted to their environment survive and reproduce in greater numbers, resulting in the increase of the frequency of the advantageous allele within the population

Question 25

natural selection process

Answer 25

variation exists within a population caused by mutation, better adapted individuals more likely to survive and reproduce, these organisms are more likely to pass on their alleles, those which are less adapted fail to survive and reproduce, these organisms are less likely to pass on their alleles
organisms subject to selective pressures, selection pressure determines the spread of an allele within the gene pool

Question 26

Biotic factors that influence selection

Answer 26

predator, pathogen, food source, human activity, competition

Question 27

abiotic factors that effect selection

Answer 27

temperature of…, light intensity, soil PH, wind speed, O2 concentration, salinity, precipitation, humidity, ASPECT

Question 28

stabilizing vs directional selection

Answer 28

stabilising- against both extremes- only mean phenotype will have reproductive success, alleles for mean phenotype are passed on to future generations, frequency of mean alleles increases. alleles coding for extreme phenotype decreases

directional- selection for one extreme, individuals with advantageous allele have increased reproductive success, alleles for one extreme passed on, frequency of this allele increases, alleles coding for both extremes decreases