Biology - DNA, RNA, and Protein Synthesis

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Notecards to study for out Test on Wednesday on DNA, RNA, and Protein Synthesis

DNA stands for...

Deoxyribonucleic Acid

It's basic twisted structure is called...

double helix (like a twisted ladder)

Composed of repeating...

nucleotides

What is a nucleotide?

Units of a long molecule that make up DNA; their sequence carries the genetic information of an organism

Nucleotide is made of ...

1) Sugar (Deoxyribose)
2) Phosphate (phosphoric acid)
3) Nitrogen base (A, G, C, T)

the "backbone" of DNA is made of ...

sugar and phosphate

The 4 nitrogen bases in DNA are...

adenine, guanine, cytosine, thymine

Purines are...

A, G (adenine, guanine)

pyrimidines are...

C, T (cytosine, thymine)

Complimentary base pairs

A with T
G with C

Function of a nucleotide...

- Genetic info with structures for making proteins
- Every organism is composed of the same four nucleotides

Process of copying DNA is called....

replication

The result of DNA replication is ___ new strands of DNA, giving a total of ___ strands of DNA

2, 4

When does DNA Replication take place?

Before the cell enters either mitosis or meiosis

How does replication take place? (steps of replication are...)

1) Ladder untwists
2) Ladder unzips
3) Left forms a new right side by base pairing
4) Right forms a new left side by base pairing
5) Ladder zips and twists

RNA stands for...

Ribonucleic acid

Basic structure of RNA is....

1) Single Stranded
2) Composed of nucleotides

Nucleotide structure in RNA

1) Sugar = ribose
2) Phosphate = phosphoric acid
3) Nitrogen bases are A, U, G, C

Differences/Similarities between DNA and RNA nucleotides/structure

1) DNA is double stranded and RNA is single
2) Sugar of DNA is deoxyribose, sugar of RNA is ribose
3) Nitrogen bases of DNA are A, T, G, C and bases of RNA are A, U, G, C

Nitrogen bases of RNA are...

A, U, G, C (U is uracil)

Three main types of RNA...

Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)

mRNA...

- Long single strand
- Function: carry the DNA code from the nucleus to the ribosome

tRNA...

- Short folded strand with 3 bases
- Function: read the code from mRNA and collect the correct amino acids to build a protein

rRNA

- Hamburger bun shaped
- Helps build ribosome that will assemble protein (like part of the factory)

How is RNA formed?

Transcription

What is transcription?

The formation of RNA

Where does transcription take place?

In the nucleus

The steps of transcription are...

1) DNA untwists and unzips
2) RNA forms from one side of the DNA (template) by base pairing
3) RNA detaches and leaves nucleus
4) DNA zips up and twists

Transcription happens in a similar way as the DNA process of...

Replication

During transcription, if the DNA template was ACCAACCGAGT, it would be transcribed to...

UGGUUUGGCUCA

What is a codon?

Each set of 3 nitrogen bases that codes for an amino acid (each mRNA triplicate)

mRNA is read as a _______ code

triplicate

3 mRNA bases code for 1 _____

amino acid

Because there are 4 different bases (A, U, G, C), there __(#?)__ triplets, which are called _____.

64 triplets that are called codons

How many amino acids are there?

20 amino acids

An overview of protein synthesis...

1) In the nucleus, DNA→mRNA (transcription)
2) mRNA leaves nucleus and goes through cytoplasm to find a ribosome
3) Anticodon of tRNA matches with codon of mRNA to form an amino acid chain → protein (translation)

What is translation?

decoding of an mRNA message into a polypeptide chain (protein)

Translation is to convert from language of _____ into the language of _____.

from language of nucleic acid into language of amino acid

Steps of Translation

1) mRNA leaves the nucleus and travels through cytoplasm to a ribosome
2) mRNA "shares" the code of tRnA
3) tRNA translates code and collets the proper amino acid and brings it to ribosome
4) Ribosome joins amino acids to make protein

What and where is an anticodon?

three unpaired bases on tRNA

Metaphor: DNA ...

architect

Metaphor: mRNA ...

blue print

Metaphor: ribosome ...

construction site

Metaphor: tRNA ...

construction workers

Metaphor: amino acids ...

materials

Metaphor: protein ...

finished building

What is a mutation?

change in DNA (change in proteins caused by change in DNA)

Mutation in body cell (does/does not) cause a change in offspring?

does not

Mutation in reproductive cell (does/does not) cause a change in offspring?

does

What is a point mutation/substitution?

Change in a single base pair in DNA

Cancer happens when there is a change in ____.

cell division

point mutation/substitution affects protein
synthesis..

one base is changed to another, affects usually no more than a single amino acid

One point mutation/substitution is...

sickle cell anemia

What is a frameshift mutation?

When a single base pair is added or deleted and the bases are still read in groups of 3, but the groupings are shifted for every codon that follows; shift of the "reading frame"

Frameshift mutation is also called...

insertion/deletion

insertion/deletion affects protein synthesis...

base inserted or removed from the DNA sequence and thus every base after the first "wrong" one is also wrong because it is shifted (every codon after deletion or insertion will be affected)

A chromosomal mutation is...

Chromosomes break, get lost, rejoin incorrectly--> a mutation that involves a change in the number or structure of chromosomes; can change the locations of genes on chromosome; possibly could change the number of copies of some genes

Four types of chromosomal mutations...

deletions

additions/insertions (would both cause frameshift mutations)

inversions (breaks off, flips, and rejoins incorrectly)

Translocation (breaks off of one chromosome and is added to another)

chromosomal mutation is especially common in ...

plants

A mutagen is...

environmental cause of mutation; an agent that causes a genetic mutation

Causes of mutations...

spontaneous, environment (radiation, chemicals, high temperature)

How could a mutation be fixed?

enzymes proofread DNA and replace or fix incorrect nucleotides

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