Transcript How does DNA control cell activities?

How does DNA control cell
activities?
Protein Production
• The sequence of nucleotides in DNA
contains instructions for producing
proteins.
• What are proteins?
• Which cellular organelles are associated
with the production of proteins?
What are proteins?
• Polymers constructed from long chains of
amino acids.
– Peptide bonds join together amino acids.
• Proteins regulate cell functions.
• Comprise filaments in muscle tissue
• Enzymes control chemical reactions in a cell
– Breaking down glucose
– Forming spindle fibers in mitosis
How many types of nucleic
acids are found in your cells?
• DNA
– Deoxyribonucleic Acid
– 5-Carbon Sugar = Deoxyribose
– Double-stranded
• RNA
– Ribonucleic Acid
– 5-Carbon Sugar = Ribose
– Single-stranded
RNA-What does it do?
• Same nitrogenous bases as DNA…EXCEPT
thymine is replaced with URACIL
• Uracil pairs with Adenine
• Takes instructions from DNA and builds
proteins amino acid by amino acid.
How many types of RNA help
build proteins?
• mRNA
– Messenger RNA
– Copies instructions from DNA in nucleus
– Brings instructions from nucleus to the
cytoplasm to the ribosome
– CODON
• Three nucleotide sequence that codes for a
specific amino acid
How many types of RNA help
build proteins?
• rRNA
– Ribosomal RNA
– Composes ribosomes
– Binds to mRNA and uses instructions to
assemble amino acids in the correct order
How many types of RNA help
build proteins?
• tRNA
– Transfer RNA
– Delivers amino acids to ribosome for protein
assembly
– ANTICODON
• Three-nucleotide sequence attached to amino acid.
• Complimentary to mRNA codon
Process of protein synthesis
• http://www.lewport.wnyric.org/JWANAMA
KER/animations/Protein%20Synthesis%20
-%20long.html
Two Parts of Protein Synthesis
• TRANSCRIPTION
– Occurs in nucleus
– mRNA gets information from DNA and takes
out to ribosomes
• TRANSLATION
– Occurs at ribosomes in cytoplasm
– Converts information in mRNA sequence into
a sequence of amino acids in a protein
Transcription Process
• Enzymes unzip DNA molecule in specific location
• Free RNA nucleotides form complimentary base
•
•
pairs with the nucleotides on the DNA strand
mRNA strand breaks away and DNA strand
rejoins
mRNA strand leaves the nucleus and enters the
cytoplasm through nuclear pores
Translation Process
• For protein assembly, different amino
acids in cytoplasm must be delivered to
the ribosomes
• Each tRNA molecule attaches to a specific
amino acid
• tRNA ANTICODONS pair with
complimentary mRNA CODON
Translation Process
• Amino acids form peptide bonds with each
other to form long chains called
POLYPEPTIDES or PROTEINS
• This process continues until a STOP codon
is reached
Translation Process
• Then the amino acid chain breaks off and
twists into a complex 3D shape
• Different proteins = Different cell
structures and enzymes