Biology Unit 5 test

Frederick Griffith (what did he study and what was his experiment)

Studied the connection between bacteria and pneumonia

Experiment: Injected mice with different strands of bacteria

What happened when mice were injected with Rough Bacteria?

Survived

What happened when mice were injected with smooth Bacteria?

died

What happened when mice were injected with heated smooth Bacteria?

survived

What happened when mice were injected with Rough and smooth heated Bacteria?

died

What were the results of Griffith’s experiments?

Some “factor” changed the harmless - rough bacteria into the disease causing bacteria

What did Oswald Avery want and what was his experiment and results?

Wanted to figure out what “factor” caused transformation

Experiment:

Tested to see if transformation occurred without a specific macromolecule

Conducted the same experiment as Griffith, but included specific enzymes that broke down each of the four macromolecules

Result:

Determined nucleic acids caused transformation

what did Alfred Hershey & Martha Chase do?

Worked with bacteriophages to determine if DNA or RNA carried genetic information

What are bacteriophages? And how do they infect becterium?

Viruses that infect bacteria

Usually composed of a DNA core and protein coat (RNA)

How a bacteriophage infects a bacterium:

By injecting their DNA into a bacterium and it gets incorporated into a bacteria plasmid

what experiment did Alfred Hershey & Martha Chase do? And what were the results?

Used isotopes of sulfur and phosphorus as markers to determine what holds genetic information.

Sulfur - 35 marked the protein coat to see if touch caused the transformation

Phosphorus - 32 marked the DNA core to see if injection caused the transformation

Result:

DNA contained the genetic information

What monomer makes up DNA?

Nucleotides

What are the 3 components of DNA?

5 - Carbon Sugar: __**Deoxyribose**__

Phosphate Group

Nitrogenous Base 

What are purines and their structure?

Purines have a 2-ring nitrogenous base.

Adenine

Guanine

What are pyrimidines and their structure?

Pyrimidines have a 1-ring nitrogenous base.

Cytosine

Thymine

(and uracil when applicable)

What did Erwin Chargaff do and notice?

Studied DNA and noticed that:

There were equal amounts of Adenine & Thymine

There were equal amounts of Cytosine & Guanine

What did Rosalind Franklin do and notice?

Took a detailed picture of DNA by using x-rays

First noticed that DNA was double stranded

What did Watson and Crick do and notice?

Used Franklin’s picture to construct a 3D model of DNA and claimed that it was in a double helix shape

Noticed hydrogen bonds connected the two strands (nucleosides)

3 hydrogen bonds between C and G

2 hydrogen bonds between A and T

Double helix structure

Twisted ladder of DNA on a molecular level

Histone structure

individual protein

Nucleosome structure

Cluster of DNA wrapped around histones

Chromosome structure

Condensed DNA

Chromatin structure

Less condensed DNA

What direction do you read a DNA strand?

5’-3’

What does it mean for DNA to be anti-parallel

It means that the DNA strands are the complement to the ones they are opposite of.

Why do we need to replicate DNA before cells divide?

So that each cell has a copy of our DNA

DNA replicates in what phase of the cell cycle?

Interphase

After replication, how many strands of DNA will be made?

2

What does Helicase do?

An enzyme called helicase unzips the DNA strand by depolarizing the hydrogen bonds hold the two strands of DNA together

What is DNA naturally?

Hydrophobic

The point where the DNA is unwound is called what?

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Replication fork

After the DNA is unzipped, what happens?

It will rotate 180 degrees

How are new strands of DNA created?

DNA polymerase binds to the original strand of DNA with the help of a primase(which act as signal markers) and creates new strands of DNA.

What will the new strands do?

Each new strand will complement the nucleotides of the original strand of DNA.

How is the leading strand made?

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Continuously

How is the lagging strand made?

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In chunks

What are the “chunks” of DNA fragments called?

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Okazaki Fragments

What enzyme connects bases?

An enzyme called DNA Ligase connects the bases to form the new DNA strand.

What does helicase do (simple version)?

unzips the DNA

What does Primase do?

puts down primers to show where DNA Polymerase needs to begin

What does DNA polymerase do?

creates the new strand of DNA; proof reads and checks the DNA

What does DNA ligase do?

connects the strands together

Why is the process of DNA replication described as semi convservative?

Because after DNA is replicated, the new DNA will have one strand that is new and one that is the original.

DNA vs RNA

DNA: Deoxyribose, Double stranded, has Thymine

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RNA: Ribose, Single stranded, Uracil

What is the main purpose of transcription?

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To turn DNA codes into RNA codes

Where does transcription occur?

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In the nucleus

What is RNA Polymerase’s role in transcription?

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RNA polymerase binds to a strand of DNA and makes an mRNA copy of the DNA strand

What does Messenger RNA (mRNA) do?

Carries copies of instructions on how to turn amino acids  into proteins

What is Ribosomal RNA (rRNA)?

Located on the ribosome and feeds in the mRNA strand

What does transfer RNA do (tRNA)?

Transfers mRNA code into to the ribosome and releases an amino acid

What are introns and extrons?

Introns: the parts that are removed.

Exons:  the parts that remain and get expressed

What is the main purpose of translation?

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So that mRNA connects with the ribosome.

Where does translation occur?

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In the ribosome (the cytoplasm of the cell)

How many bases make up a codon?

3

When dealing with Deciphering the Genetic Coding the codon ciphers, which type of RNA would you use?

I would use the original RNA not the anticodon that comes from the tRNA

Steps of Translation

1. mRNA brings the information to the ribosome through the rRNA
2. A tRNA corresponding to the mRNA binds to the mRNA


1. The anticodon for the tRNA binds to the codon of the mRNA
3. Once the anticodons attach, the tRNA releases its amino acid
4. The ribosome connects the different amino acids together to form a polypeptide (polymer)

What kind of bond holds amino acids together?

Peptide bonds

what happens during replication transcription and translation

Replication

DNA is copied

Transcription

turns DNA codes into RNA codes

Translation

mRNA connects with the ribosome.

what is epigenetics?

the study of how DNA interacts with epigenetic tags inside the cell

List the two ways that DNA/histone expression can be changed:

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1. DNA Methylation: Methyl groups added to turn off the DNA
2. Histone Modification: Chemical groups can be added or removed from histones to make the histones more tightly or loosely

What do Hox Genes do?

These tell the order and how an organism will develop

What is a mutation?

any change in the genetic material of an organism

Gene mutations:

Changes in one or a few nucleotides that affect a gene.

Also known as a point mutation because they occur at a single point in the DNA

Chromosomal mutations:

mutations that can change a chromosome’s structure or number.

Why are gene mutations also known as point mutations?

Because they occur at a single point in the DNA

Point Mutation: Substitution

Switching a nucleotide for another

Types:

Silent - No change in AA sequence

Nonsense - changes sequence into a stop codon

Missense - changes the Amino Acid

Point Mutation: Inversion

When sequences of DNA are reversed

Insertion

Adding a base into the DNA sequence

Deletion

Removing a base from the DNA sequence

What type of mutations are deletion and insertion?

Frameshift

What happens in Deletion Duplication Inversion and Translocation

Deletion:

The loss of a section of a chromosome.

Duplication:

Produced extra copies of a section in a chromosome.

Inversion:

The reversal of a section in the chromosome

Translocation:

Only mutation that involves 2 different chromosomes.

The swapping of sections between two chromosomes

Nondisjunction

A numerical chromosomal disorder.

Failure of chromosomes to separate correctly during meiosis (sex cell reproduction).

Causes sex cells (sperm and eggs) to have too many or too few chromosomes

Switch cards around

Yup

nuclear membrane

What is number 1?

RNA polymerase

What is number 2?

RNA nucleotides

What is number 3?

DNA

What is number 4?

mRNA

What is number 5?

template strand

What is number 6?

Amino acids

What is number 1?

Protein

What is number 2?

Large subunit

What is number 3?

Small subunit

What is number 4?

Codon

What is number 5?

tRNA

What is number 6?

mRNA

What is number 7?