Download DNAandProteinSynthesis

DNA and RNA
Transcription and Translation
Comparing Nucleic
Acids
RNA
DNA
• Double strand
• Thymine
• Deoxyribose
Sugar
• In eukaryotes,
inside nucleus
•
•
•
•
Single strand
Uracil
Ribose Sugar
Can travel in
and out of the
nucleus
through
nuclear pores
Three types of RNA
• mRNA
– Messenger RNA
– Created based on a gene on DNA
• rRNA
– Ribosomal RNA
– Reads mRNA and assembles materials needed to
build proteins
• tRNA
• Transfer RNA
• “Taxi”
• Bring materials (amino acids) to the
ribosome
• What is DNA replication?
• When would a cell need to replicate its
DNA?
When the cell is ready to divide!
• could be for growth, or to
repair injury
Transcription and
Translation
• What are proteins?
– Proteins are a large molecule important to living
things
– They are made of CHON (carbon, hydrogen,
oxygen, nitrogen)
– They are built from building blocks called “amino
acids”
• How does a cell know how to build proteins?
– DNA carries all the instructions for a cell
•
Transcription and
Translation
What jobs do proteins have?
– proteins have many critical roles in living things
– Antibodies: fight off foreign particles (like
virus/bacteria)
– Enzymes: run chemical reactions in cells
– Hormones: messenger proteins that travel
• Protein Synthesis is a 2-stage process
1. Transcription: make mRNA from DNA
gene
2. Translation: read mRNA and build protein
Transcription and
Translation
• How does DNA hold information?
– Information is found in the order of nitrgoen bases
in DNA (the order of A,C,T, and G’s)
• Where is DNA located?
– Nucleus of a cell (eukaryotes)
• In which organelle do cells build proteins?
– Ribosomes
Genes
• What is a GENE?
– A gene is a segment of DNA that gives
instructions to build ONE specific
protein.
– If DNA is a cookbook, each recipe is a
gene.
– Every cell in your body has the whole
cookbook, but only uses some recipes.
Genes
•Exon: part of DNA sequence expressed
•Intron: long noncoding sequences
Transcription and
Translation
Enzymes make an mRNA copy of a portion
of DNA
• Occurs in the nucleus
• Why can mRNA leave the nucleus, but
not DNA?
Size of the mRNA is small enough to escape the nuclear pores
• Where does mRNA go after transcription?
Ribosomes! Made of r-RNA!
• mRNA is read and the tRNA bring amino
acids in order to it build proteins!
1. Helicase enzyme unzips the DNA
2. RNA polymerase reads the selected gene and
adds the appropriate RNA nucleotides
3. RNA processing: the introns are cut out
4. The mRNA strand breaks away and DNA
rejoins.
5. mRNA can now leave the nucleus and head to
the ribosome
• There are only ___ nitrogen bases in the
“language” of DNA.
• There are ___ different amino acids that
can be used to build a protein.
• How can 4 bases form a code for all 20
amino acids?
- By using a codon of three letters for
each
• Read in groups of three letters: CODON
• (DNA gene) AAA GTG GCC
ACT
• (mRNA)
UUU CAC CGG UGA
• Read in groups of three: ANTI-CODONS
• UUU CAC CGG UGA
(mRNA)
• AAA GUG GCC ACU
(tRNA)
• t-RNA is the taxi that brings the amino
acids to the Ribosome
mRNA:
Amino acids
UUU CAC CGG UGA
PHE HIST ARG stop
Ribosome and tRNA
• Summarize the steps of Protein Synthesis.
• Describe the three types of RNA.
• Relate chromosome, gene, sister chromatids
and DNA.