Topic 7

Question 1

Extant vs Extinct

Answer 1

-1.7 million extant species (1/5 of the estimated number currently existing)

-most species are extinct
(10 X the number of species currently existing)

Question 2

Cellular

Answer 2

-both prokaryotes + eukaryotes have a cellular base

Question 3

ATP

Answer 3

-primary energy source amongst species

Question 4

Central Dogma

Answer 4

-transcription and translation

Question 5

Genetics

Answer 5

-study of heredity and variation in cells, individuals and populations

• the study of genes

Question 6

Gene

Answer 6

-functional unit of heredity and variation

Question 7

Molecular Genetics

Answer 7

-molecular genetics is the study of structure and function of genes at the molecular level

Question 8

Why the Study of Molecular Genetics is Important

Answer 8

-human health

-forensics

• agriculture

-environment

• evolution

Question 9

Gene

Answer 9

-specific DNA sequence that codes for a specific mRNA (and protein)

Question 10

Genome

Answer 10

• all the genetic information of an organism (entire DNA sequence)

Question 11

Allele

Answer 11

-variant forms of a gene caused by difference in DNA sequence

Question 12

Genotype

Answer 12

• the specific genes inherited by an individual ( can be similar between individuals)

Question 13

Phenotype

Answer 13

-visible traits

• has an environmental component

Question 14

Gene Expression

Answer 14

-“turning on” a gene to produce RNA and protein

-turning the genotype into the phenotype

• follows the central dogma of biology

Question 15

Transcription vs Translation

Answer 15

-transcription makes RNA

• translation makes protein

Question 16

Protein Expression

Answer 16

-specifies phenotype

-amount of protein made varies in population

-the type and abundance of proteins in the cell

-although DNA is the information molecule that directs protein expression, proteins ultimately determine the phenotype of the cell because they are the trait encoded by DNA

Question 17

Enzymes

Answer 17

-catalyze the synthesis and transformation of all biomolecules

Question 18

Structural Proteins

Answer 18

-maintenance of cell shape

Question 19

Signalling Proteins

Answer 19

• hormones and receptors

Question 20

Phenotypic Variation

Answer 20

1. Different Alleles

-slight variation in gene sequence results in change in amino acid sequences of proteins - leads to changes in the function of proteins

2. Different Regulation of gene and protein expression

-unique alleles in differential regulation of thousands of genes among individuals leads to unlimited phenotypic possibilities

-Individuals that possess similar alleles and gene regulation leads to more similar protein expression (immediate family, relatives) and phenotypes

Question 21

Heredity/Inheritance

Answer 21

-the transmission of traits from one generation to the next

-A trait is any characteristic of an individual that is heritable (part of your genetic code)

-humans have been studying inheritance for centuries

-breeding crops and livestock artificially select for desirable traits

Question 22

Gregor Mendel

Answer 22

-studied inheritance and garden peas in 1865

-tracks changes in flower colour (and other characteristics) and thousands of pea plants

-worked out a mechanism showing how traits from one generation could be passed down to the next

-Heritable traits results from a mixing of particulate factors

Question 23

Proteins and DNA in Chromosomes

Answer 23

-Proteins (50-60%)

-composed of 20 amino acids
-millions of possible 3-D structures
-complex enough to store a heritable information

-DNA (40-50%)

-composed of four nucleic acids
-Simple and limited 3-D structures
-thought to play a structural role

Question 24

Establishing DNA as the Hereditary Molecules (3 Experiments)

Answer 24

-griffith: discovered, genetic transformation that genetically altered streptococcus pneumonia

2. Avery, Macleod, McCarthy: identify DNA as the molecule that transforms S. pneumonia
3. Hershey and Chase: found the final evidence establishing DNA as the hereditary model

Question 25

Chromosome Theory of Inheritance

Answer 25

-scientist noted that chromosomes fit Mendel’s hypothesis -Individuals have two copies of each chromosome -similar homologous chromosome separate independently during meiosis -gametes: have one copy of each chromosome -zygotes: are a random combination of two gametes

Question 26

Streptococcus Pneumoniae

Answer 26

-Bacterial pathogen that causes pneumonia in mammals -a significant cause of child mortality before the development of antibiotics and vaccines

Question 27

Smooth (S) Strain

Answer 27

Virulent- causes disease -capsule protects S cells from the immune system well enough to cause disease

Question 28

Rough (R) Strain:

Answer 28

-lacks polysaccharide capsule, cannot evade the immune system, therefore is benign

Question 29

Griffith Experiments

Answer 29

1. Virulent Bacteria (S-strain) *mouse dies of pneumonia 2. Non-virulent *mouse remains healthy 3. Heat-killed Virulent Bacteria *mouse remains healthy 4.Heat-killed Virulent Bacteria and nonvirulent bacteria * mouse dies of pneumonia

Question 30

Griffith,s Conculsion

Answer 30

-Some molecules released when the cells died, could transform living R cells into living S cells -transformation was permanent and heritable (all progeny cells in the colony were the same type) -the transforming principal

Question 31

Avery, MacLeod, and McCarthy

Answer 31

-Hypothesis: transforming principle could be protein, DNA or RNA -Experimental Approach: eliminate each type of molecule in S cells and see whether transformation of R cells into the virulent form still occurs -Conclusion: if transformation stops when one type of molecules absent the missing molecule is a transforming principle, therefore is the genetic material

Question 32

Avery et al. Experiments

Answer 32

-kill S cells, lyse the cells, remove the lipids and sugars -Test one: Add Protease (breaks down proteins) -Test two: Add RNAse (breaks down RNA) -Test three: Add DNAse (breaks down DNA) -add living R cells to each tube -look for living S cells -Mouse survived in the tube without DNA

Question 33

Nail in the Coffin

Answer 33

-the Hershey and Chase experiment provided further evidence that DNA is the genetic material -used bacteriophage (viruses that infect bacteria) and it’s E. coli host to show that DNA is the transforming principle

Question 34

Life cycle of the Bacteriophage

Answer 34

-Lyric Infection: massive reproduction of virus, resulting in host cell lysis -after attachment, the virus, genetic material is injected into the host, and the phage coat remains outside -viral DNA takes over the host, hundreds of copies are made, and progeny virus burst from the host -DNA uses phosphorus, but never sulphur -some amino acids use sulfur, but never phosphorus -3 experiments develop two populations of virus -One with radioactive phosphate (32P) -One with radioactive, sulphur (35S)

Question 35

Results of Hershey and Chase Experiment

Answer 35

-experiment one: 35S not found in host cells or progeny virus particles. Therefore, protein is not the genetic material -Experiment two: 32P found in host cells in progeny virus particles therefore DNA is the genetic material