DNA: TIMELINE OF PEOPLE
Use CH 12 (p. 287) to create a timeline of the People Important to DNA
(Left side = Scientists’ Name; Right Side = Their Achievement)
DNA: The Double Helix
What is DNA???
· Your “genetic” information (______)
· ______
· DNA is an example of a Nucleic Acid à which is an Organic Compound/ Macromolecule
· The monomer (building block) of DNA is a ______ à many nucleotides join to form a long chain of DNA .
· Nucleotides have 3 parts:
o ______
o ______ (Deoxyribose)
o ______
DNA Structure: What does DNA Look Like???
· Classic “______” Shape
o Two sides of DNA are ______à parallel but go in different directions
o Must be in this shape so DNA can be compacted and fit inside of structures called
______.
o Remember you have 46 Chromosomes…. Each with SAME TYPE of DNA.
o DNA, which is located inside of chromosomes, is found in the ______ – the control center of the cell!
· The backbone /sides of the “ladder” are made up of alternating ______(Deoxyribose) & ______.
· The “steps” or rungs of the “ladder” are made of 4 major Nitrogenous bases:
o ______
o ______
o ______
o ______
______always pairs with______& ______always pairs with ______
• The Nitrogen bases are held together by weak covalent bonds called ______.
(Remember those from our discussion on water?)
DNA REPLICATION
· What is DNA Replication? When the cell makes a copy of DNA for new cell made during cell division.
· Why Replicate? In preparation for cell division (during the ______of Interphase), a cell must duplicate its genetic info (DNA) to pass on to the new daughter cells.
How Does Replication Work???
1. DNA must first be “untwisted” and “unzipped.”
2. The enzyme ______“unzips” the DNA strand – at the hydrogen bonds. A ______is formed.
3. Each DNA strand acts as a ______for the NEW strand to be formed
4. ______(protein/enzyme) binds to the DNA strand. Polymerase adds complimentary nitrogen base pairs to the un-matched nitrogen base pairs in the 5” à 3” direction (Remember DNA is ANTI-parallel so polymerase is adding base pairs in opposite directions. This way two polymerase can be working on the same DNA strand!)
5. As the polymerase moves along the DNA, it constructs a ______strand that ______each of the ______strands. Matches the nucleotides A – T and G – C.
6. The result is 2 new ______DNA molecules – one from the ______strand and one ______strand.
7. DNA Polymerase remains attached until 2 new DNA strands are created; it “______” the strands to minimize error in the process.
Practice Replication :o)
G A T C C G A A G C A C
RNA: Ribonucleic Acid
How is RNA different from DNA???
• ______
• How is RNA different from DNA???
– Has a ______instead of a deoxyribose (sugar backbone)
– ______…Not double stranded like DNA
– Contains ______( U ) instead of Thymine (T)
• ______binds with ______; G binds with C
• RNA Nucleotide consists of…
– ______ (Ribose)
– ______
– ______ (A, U, G, or C)
The THREE Types of RNA
mRNA = (______) codes for polypeptides
rRNA = (______) makes up ribosomes. RIBOSOMES are the ______builders!!!
tRNA = (______) brings the amino acids to the ribosome during protein synthesis
2 Stages in making proteins:
1) ______– using DNA template to make mRNA strand
2) ______– using mRNA strand to create polypeptides
Transcription: ______à ______
This is the process by which mRNA is produced/written (transcribed) from DNA. This process occurs in the nucleus, because DNA is TOO LARGE to leave the nucleus.
The Major Steps:
1. DNA gets unzipped by RNA polymerase.
2. The ______reads along one DNA strand and uses it as a template, reading one codon at a time.
a. ______ – groups of ____ nitrogen base pairs/ individual nucleotides that code for a specific amino acid.
b. You can think of codons as “words” in a sentence. Each nitrogen base = a letter; each codon (which are made of nitrogen bases) = a word; each codon (or word) means something in the mRNA sentence…the codons/ words code for an Amino Acid!!!!
i. To find the mRNA codes you must use the mRNA Codon Wheel
ii. “______” codon = ______(Methionine)
iii. “______” codons = UAA, UAG, and ______
iv. Example:
mRNA Strand:
U-C-A-U-G-G-G-C-A-C-A-U-G-C-U-U-U-U-G-A-G
methionine glycine threonine cysteine phenylalanine STOP
3. mRNA is produced/ ______with the complimentary nucleotides (A-U; G-C).
4. The polymerase keeps making the mRNA until a “______” codon is reached.
5. When the “stop” is reached, the new strand of mRNA ______away, leaves the nucleus through the nuclear pore, and ______to the______. This is where protein synthesis (or the creation of a protein with mRNA) begins.
6. The next major process of ______will occur at the ribosome, in the cytoplasm of the cell.
mRNA Codon/ Amino Acid wheel
Practice Replication & Transcription :o)
DNA à atg taa ccc GCA ATG
DNA à
mRNA à
Amino acid à
Translation = ______à ______& ______à ______
(polypeptides)
The synthesis of polypeptides (PROTEINS) by the ribosome using the message carried by the mRNA
What Exactly Happens during translation???
1. The ribosome attaches to the first codon of ______.
2. A tRNA ______matches up to the first codon on the mRNA – this is always AUG “start”
a. An anticodon is the complimentary base pair that matches the codon. For example, if the codon is GGA, the anticodon is ______.
3. The tRNA is carrying an ______
4. The ribosome (rRNA) ______the mRNA through and ______the next codon and ______up the correct tRNA; bringing the next amino acid into line.
5. The ribosome binds the first and second amino acids together.
6. The tRNA’s ______after they “drop off” the amino acids.
7. This process occurs over and over until a stop codon is met.
8. The result is a chain of polypeptides à______.
How does all this DNA stuff fit together???
Amino acids (aa) à Polypeptides à Proteins
There are 20 different amino acids.
Question: “What is a gene?”
Answer: “A particular segment of DNA that codes for one particular protein.”
Genetic Mutations à ______or ______in genes (DNA)
· Two Types of Mutations
– ______
– ______
1. Gene Mutations: changes in ______
– Point Mutations à Nitrogen Base Pair changes
– Examples include ______, ______, &
______
• Point mutations are the substitution, addition, or removal of a ______nucleotide
– ______: types of point mutations that shift the “reading frame” of the genetic message
2. Chromosome Mutations: changes in _____or ______of chromosome
– Deletion à
– Duplication à
– Inversion à
– Translocation à
The proteins formed by translation are responsible for all of our traits!
So what controls how genes are turned ON or OFF?
· Gene Regulation is controlled by a group of genes that operate together known as ______.
· Many times these genes must work together, in order to control a function.
– Exampleà Ecoli and the ______
• Lactose is a ______(carbohydrate) that
can be broken down into ______+
______.
• When Ecoli, is placed in a medium where it is forced to eat ONLY lactose, it must be able to breakdown lactose into these two substances.
• If Ecoli is placed in a medium that DOES NOT contain LACTOSE, it does not need to transcribe (or read) those genes… So it does not read those genes.
• ______are turned ______by ______and turned ______by ______!!!
• The repressor protein is always present on the genes of Ecoli. It is bound to the ______, the section of DNA that surrounds the area where the genes for breaking down lactose are located. The only way for ______to transcribe these genes, is if the repressor protein is moved .
• To do this, lactose will bind to the lac repressor and move the repressor protein away = RNA Transcription!!!
______are controlled individually and have regulatory sequences that are much ______than those of the lac operon found in bacteria.
______à genes within eukaryotic cells that control the organs and tissues that develop in various parts of an embryo.
· Mutations in these genes can completely change the organs that develop in specific parts of the body!!
o EXAMPLE: Drosophila (common fly) replacing their antennae with LEGS growing out of their heads!!!!