___________________ - was the 1st to identify genetic material – exhibited transformation with encapsulated and non-encapsulated bacteria – was able to prove that DNA is the genetic material
___________________ - repeated Griffith’s work – discovered that ________ is the nucleic acid that store & transmits the genetic information from 1 generation of an organism to the next
____________________ - used bacteriophages & E. coli to prove that DNA is the genetic material (phosphorus was injected into the bacterium and not sulfur)
The Structure of DNA
DNA is a long, thin molecule made of subunits called ________________________ that are linked together like a chain. The 3 parts of a nucleotide are the
1. _______________________
2. _______________________
3. _______________________
The sugar molecule and the phosphate are the same for all nucleotides – only the bases differ.
_________________________ is the scientist who discovered the base-pairing rules for DNA. In DNA, Adenine always pairs with ___________________ and cytosine always pairs with ________________.
________________ & _____________ discovered the 3-dimensional ____________________ that represents the shape of DNA. It looks like a spiral staircase with 2 strands of nucleotides wrapped around the axis. Each rung is a purine or pyrimidine held together by a hydrogen bond. The strands are complements of each other.
REPLICATION
When DNA is replicated, that means it is synthesizing a new strand. The DNA must 1st be unwound. This is accomplished by ____________________ that break the hydrogen bonds. The ____________________ is the point where it unzips. This forms a y shape. At the fork, DNA polymerases move along strands of DNA adding ________________________ to exposed bases. Two new double helices form that eventually get the signal to detach. The DNA polymerase also has the ability to “proofread” the strand to check for mistakes. The molecules may have many forks throughout the molecule moving in separate directions that causes it to form bubbles.
GENE STRUCTURE
Much of the DNA of an organism does not code for protein. Most genes are interrupted by long segments of nucleotides that have no coding information (kind of like fillers in medications). The noncoding sequences are called ______________________ while those that code for amino acids are called ______________________ because they are expressed. Introns are believed to add genetic flexibility to organisms by shuffling. In a long sequence, the ____________ are chopped out and a short ___________ sequence is made that actually forms the protein.
______________________ ___________________ are clusters of almost identical sequences of genes. These families are used to trace evolution. An example of this in the human body is with _____________, which has 12 different genes in 2 different families that are active in different times of life.
_______________________________ are genes that have the ability to move from one chromosomal location to another. They are sometimes called “jumping genes.” When they move from one location to another, they may inactivate a gene or cause mutations. These may influence evolution. These were discovered by ________________ ____________________ in the 1950s.
_________ is an example of a gene that can protect cells from mutations such as in cancers.
__________ contains the working instructions for the cell. It consists of a single strand of nucleotides (DNA is double), a 5 carbon sugar called ribose (DNA had deoxyribose), and uracil rather than thymine as a base.
RNA is present in cells in 3 different forms, each with a different function. The three forms are ___________, _______________, & ______________. All 3 types are essential for processing the info from DNA into proteins. This process is called ____________ ___________________. This occurs in 2 stages:
1. ____________________ - the info in DNA is transferred to mRNA
2. ____________________ - the info in mRNA is used to make a protein
This may be summarized as DNA ---------> RNA ---------> protein
Transcription Translation
Transcription in eukaryotes occurs in the ________________ and in prokaryotes occurs in the __________. It begins when ___________________________ binds to a promoter region. A promoter is a specific sequence of DNA that acts as a “start” signal for transcription. The molecule begins to unwind and the double helix is separated. This exposes the __________. Only 1 strand of DNA serves as the template. The polymerase moves down the strand like a train on a track and pairs the exposed base to its ________________________________. These are linked with covalent bonds. It can work at a rate of 60 nucleotides/second. This continues until it reaches a ___________ signal on the terminator. The enzyme is released from DNA and RNA is released into the cell for the next stage.
Transcription manufactures 3 types of RNA.
_________________________ - is an RNA copy of a gene used as a blueprint for a protein. It carries hereditary info from DNA and delivers it to the site of translation.
_________________________ - acts as an interpreter molecule – its translates mRNA into amino acid sequences
_________________________ - play a structural role in ribosomes
mRNA is built after transcription. The ______________ are cut out and _______________ join to form the mRNA. It leaves the nucleus through ____________ and enters the cytoplasm.
_______________ contain the instructions for building proteins. They consist of a 3-nucleotide sequence that corresponds either to an amino acid or a stop signal. The ______________ ___________ represents the amino acids and stop signals that are coded by each of the possible mRNA codons.