RNA & Protein Synthesis

RNA & Protein Synthesis

DNA --> RNA --> Protein

Objectives

• I can compare and contrast DNA and RNA (structure and function).

• I can describe transcription and can make mRNA from DNA.

• I can describe translation and can make a protein from mRNA.

Differences between DNA and RNA

• Sugar: DNA uses deoxyribose while RNA uses ribose

• Bases: DNA uses thymine (T) while RNA uses uracil (U)

• Shape: DNA is a double helix while RNA only has one strand

• Location: DNA is only in the nucleus while RNA can also be in the cytoplasm

What does DNA do?

• DNA is the boss of the cell, holding all of the genes (instructions) that the cell needs.

• It carries the genetic information.

• DNA cannot leave the nucleus (except during cell replication).

What does RNA do?

• Since DNA must stay in the nucleus, RNA does all of the jobs for the DNA.

• RNA carries the information from the DNA.

• RNA carries the amino acids for proteins.

• RNA builds the proteins as the DNA instructs, using the amino acids.

Multiple Choice

In RNA, uracil takes the place of the DNA nitrogen base...

• guanine

• cytosine

• thymine

• adenine

Multiple Choice

Which of the following statements is true?

• DNA is single-stranded
• RNA is single-stranded
• DNA contains uracil
• RNA contains deoxyribose

Multiple Choice

What type of sugar is used in RNA?

• deoxyribose

• glucose

• fructose

• ribose

Multiple Choice

What base does RNA have that DNA does not?

• uracil

• thymine

• cytosine

• guanine

DNA --> RNA --> Protein

The Central Dogma of Biology

Central Dogma of Biology

• DNA controls everything, but it cannot leave the nucleus.

• DNA is transcribed (copied) into mRNA.

• mRNA takes the instructions to the ribosomes (rRNA) in the cytoplasm.

• Ribosomes (rRNA) use transfer RNA (tRNA) to translate (change) the mRNA into proteins.

• DNA --> RNA --> Proteins

Three types of RNA

• mRNA - Messenger RNA which carries instructions from the DNA

• rRNA - Ribosomal RNA which builds the proteins

• tRNA - Transfer RNA which carries amino acids

Multiple Choice

Which of these is not a type of RNA?

• mRNA

• nRNA

• rRNA

• tRNA

Multiple Choice

Which kind of RNA is a messenger that carries the instructions from the DNA to the ribosomes?

• mRNA

• rRNA

• tRNA

DNA --> RNA

Transcription

Transcription

• Copies the code from the DNA to mRNA

• Takes place in the nucleus (with the DNA)

• Uses complementary base pairing to turn DNA into mRNA

Note

• RNA does not use thymine (T)

• Instead, it uses another base called uracil (U)

• So adenine bonds with uracil and guanine bonds with cytosine

• A-U and G-C

DNA: TAG CCT AAA GTC

RNA: AUC GGA UUU CAG

Transcription copies by complementary base pairing (notice the U's?)

Vocab Time!

• Codon: A set of three bases (ex. CAG)

• Anticodon: The complement to a codon, only found on tRNA (ex. GUC)

Multiple Select

Which two complementary pairs are correct for RNA?

• G-C

• A-T

• A-U

• C-T

Multiple Choice

What is the complementary mRNA sequence for this DNA codon?

GGA

• CCU

• CCT

• GGT

• AAC

RNA --> Protein

Translation

Translation

• Changes the mRNA code into a protein

• Each codon on the mRNA meets the anticodon on the tRNA

• The codons each have a specific amino acid

The Codon Table

• Gives us away to translate mRNA codons into amino acids

• Find the place where the bases in the codon overlap

• For example, the codon AUG gives us "Met" (which stands for methionine, an amino acid)

The Codon Wheel

• Like the codon table, gives us a way to translate mRNA codons into amino acids

• Work from the inside to the outside

• For example, the codon GAC gives us "Aspartic acid" (an amino acid)

Multiple Choice

What is the amino acid for the mRNA codon UUC?

• Phe

• Met

• Gly

• Stop

Multiple Choice

What is the amino acid for the mRNA codon UAC?

• Tyrosine

• Histidine

• Serine

• Valine

Review

• DNA --> RNA --> Protein

• DNA is transcribed into mRNA.

• The mRNA carries the message out of the nucleus to the ribosomes (rRNA) in the cytoplasm.

• The ribosomes work codon by codon to translate the mRNA into a protein.

• Each tRNA brings a specific amino acid to add, based on matching its anticodon to the mRNA codon.

Poll

How confident do you feel about describing RNA and Protein Synthesis?

I am...

• Very Confident

  (I could teach this)

• Confident

  (I know this well)

• Fine

  (I learned some things)

• Uncertain

  (I have many questions)

• Lost

  (I am very confused about this)

Open Ended

Using everything you have learned here, describe how cells use their DNA to make proteins.

Use as many of these words as you can:

DNA, gene, RNA, mRNA, rRNA, tRNA, codon, anticodon, transcription, translation, amino acid, protein