BIO 243 THEME 1A

What is genetics?

the stud of heredity and variation in cells

What are genes?

the functional unit of heredity and variation

What are alleles?

different versions of the same genes

What is your genotype made up of?

an individual’s complete set of alleles

What is genotype?

allele combinations you have

What is phenotype?

visible/observable traits

What is a genome?

genetic material of an organism

* entire DNA sequence of an organism

Where are genes found? What are they part of

• found on chromosomes

• parts of then genomes that encode for RNA and protein

What is coding and noncoding RNA

coding: mRNA

noncoding: tRNA

What is gene expression?

‘turning on’ a gene to produce RNA and protein

* essentially, making RNA

Which one is first, transcription or translation?

transcription

What is protein expression?

the type and abundance of protein in a cell

What do proteins determine?

they determine the phenotype of the cell because they control every reaction in the cell (i.e enzymes)

What do enzymes (proteins) do?

catalyzing the synthesis and transformation of all biomolecules

What do structural proteins do?

they maintain the cell shape

What are signalling proteins?

hormones and receptors

What makes individuals different from each other? (why do people have different phenotypes)Why do relatives look alike?

• different alleles (a slight variation in gene sequence results in changes in the amino acid sequence of proteins)

• differential regulation of gene and protein expression (more mRNA, means more proteins)

• relatives possess common alleles and gene regulation, causing them to look alike

What is the smooth strain (S) of pneumonia?

a bacterium that has a capsule that protects it from the immune system

* it is allows infection

What is the rough strain (R) of pneumonia?

bacterium that does not have the polysaccharides capsule

* can’t evade immune system, non-virulent

What was Griffith’s experiment?

• injected mice with the S strain (mice died) and injected mice with R strain (mice survived)

• heat killed the S strain and injected mice with it (they survived)

• injected mice with heat killed S strain and not heat killed R strain (mice died)

What did Griffith conclude?

the transforming principle

• concluded that something from the hear killed S strain bacteria was passed to the R bacteria that transformed them into virulent bacteria

• the transformation was permanent and heritable

What was Avery, MacLeod & McCarthy’s hypothesis?

transforming principle could be protein, DNA or RNA—which one is it?

What was Avery, MacLeod & McCarthy’s experimental approach?

eliminate each type of molecule and see whether transformation of R cells into S virulent form still occurs

What was Avery, MacLeod & McCarthy’s conclusion?

if the type of molecule is absent and transformation is gone, then this molecule is the transforming principle

What was Avery, MacLeod & McCarthy’s experiment

• they added the cytoplasm of heat killed S cells and added them into separate tubes

• in the first tube, they added RNAse (destroys RNA) and then added R cells. the however the mouse still died, so transformation still occurred

• in the second test tube they added protease (destroys protein) and then added R cells. the however the mouse still died, so transformation still occurred

• in the third tube, they added DNAse (destroys DNA) and then added R cells. the mouse survived therefore transformation was unable to occur. so DNA is transforming principle

Can viruses replicate without hosts?

no

What are the steps of viral replication?

• virus attaches to the outside of the host cell

• virus injects nucleic acid into the host

• virus hijacks cell machinery to replicate its own components

• virus is ejected from cell to infect other hosts

What is the lytic cycle?

• the final step in viral replication that bursts open and kills host cells

• massive reproduction of viruses

What are the steps of the lytic cycle?

1. phage infects a cell

2. the phage remains SEPARATE from the host DNA

3. the phage DNA replicates, new phage particles are assembled, phage proteins made

4. the cell burst open, releasing the phages

What are the steps if the Lysogenic cycle?

1. phage infects cell

2. phage DNA becomes integrated into host genome

3. the cell divides and prophage DNA is passed onto daughter cells

When can lysogeny switch to the lytic cycle?

• under stressful conditions!

• the phage DNA is excised from the bacterial chromosome and enters the lytic cycle

What was the Hershey and Chase experiment?

• they had to answer whether bacteriophages inject DNA or protein

• they labelled bacteriophage DNA and proteins with radioactive isotopes

  • 32P labelled DNA and 35S labelled Proteins

• They allowed infection of E.coli with the radioactive bacteriophage and separated the attached bacteriophage with a blender

• they saw that there were no 35S in E.coli cells in the progeny bacteriophage (not radioactive). There was 35S in the detached bacteriophage

• they say that 32p was in E.Coli cells and no 32P was found in the detached bacteriophage. 32P in progeny bacteriophage

Why did Hershey & chase use bacteriophages?

• b/c they can’t reproduce themselves

• they have to inject their heritable molecule into bacteria cell, and force the bacteria to make new viruses