DNA – Chromosomes & DNA replication – RNA & Protein Synthesis – Mutations – Gene RegulationChapter 12Pages 287 - 312

DNA & RNA

DNA• Sometimes organisms, unicellular in this case, can pass beneficial genes to other organisms that do not possess them.• EXAMPLE: in Griffith’s experiment, heat-resistant bacteria passed their heat-resistant genes to strains of bacteria that weren’t heat-resistant. What was the result? __________________________• This process is called transformation – When genes are passed from one organism to another and the recipient organism is permanently changed or “transformed”.•What is the function of DNA? To ___________ and ___________ genetic information. What do these genes “inform”? _________________•What is the structure of DNA? _________________• A bacteriophage is a type of virus that infects bacteria and can be composed of DNA or RNA and a protein coat. How do you think a protein coat serves the “phage”?•Where does a bacteriophage attach to a cell that it is attacking?

DNA

DNA• DNA is a long molecule made up of units called _____________.•What are the four nucleotides that make up a molecule of DNA?•Watson & Crick are the two scientists that are noted to have developed the double-helix model of DNA structure. Franklin studied the DNA molecule using a technique called X-ray diffraction. These are the three names you will need to be familiar with and responsible for knowing on future graded assessments.• In a double-helix structure, there are two strands of molecular structure that are wound around each other.• In a double helix, a principle that is noted is base-pairing. The “bases” involved in the structure are adenine (abbreviated “A”), thymine (T), cytosine (C ), and guanine (G). They pair via hydrogen bonding. A always bonds to T while G always bonds to C.

DNA

Chromosomes & DNA Replication• Prokaryotes lack ____________ and their DNA is located in the ______________. Most of them have a single _____________ DNA molecule containing most of all the cell’s ___________ information.• Eukaryotic DNA generally have 1000 times the __________ of DNA as prokaryotic organisms. Eukaryotic DNA is located where? ______________.• Eukaryotic chromosomes contain both _____ and protein that are tightly packed together to form a substance called ____________. This term is not new. Histones are proteins that the cell uses to “wrap up” genetic information. Refer to figure 12-10 on page 297 for a visual of the role that histones play in organizing a single cells vast genetic information. •What does “replication” mean?• During DNA replication, DNA molecules separate into two strands to produce two new strands. Each strand serves as a template. What is a template?

Chromosomes & DNA Replication• A single strand with a base pair consisting of TACGTT will produce a complementary strand consisting of ATGCAA. Remember A T and

G C in DNA (which is not exactly the same for RNA – we will get to that shortly).• But how does DNA replicate itself?• One word ENZYMES! And what type of macromolecule are enzymes? (macromolecules: lipids, carbs, proteins and nucleic acids)• These enzymes “unzip” the double helix structure and other enzymes proceed to replicate according to each base pair’s compliment, again, A T and G C.• The principle enzyme involved in DNA replication is DNA polymerase.• ETYMOLOGY TIME! Poly means ________; Polymer means ________; and –Ase always indicates an ___________.• DNA polymerase also ___________ each new DNA strand to maximize the odds that each molecule is a perfect copy of the original DNA.

Chromosomes & DNA Replication

RNA and Protein Synthesis• The first step of decoding genetic messages stored in DNA is to copy the nucleotide sequence from ______ to ________. What does DNA stand for? What does RNA stand for?•What are all nucleic acids composed of?• There are three major differences between DNA and RNA. 1) the 5-carbon sugar in RNA is ribose not ___________. 2) RNA is generally _____________. 3) RNA contains ________ instead of __________.• RNA is involved mostly in protein synthesis.•What are the 3 main types of RNA found in a cell?• Note figure 12-12 on page 300. Which of the three types of RNA is shaped like a clover…or a key?•Which type of RNA carry copies of instructions from DNA?• Ribosomes are made of which type of RNA?• The RNA type that transfers amino acids to the ribosome is called?•What is the function of a ribosome in a cell?

RNA and Protein Synthesis• The process of copying part of a DNA nucleotide sequence to a complementary RNA sequence is called_____________.•What enzyme carries the process transcription?•What enzyme is responsible for separating the double helix structure of DNA required for the process of transcription?• Promoters are signals in DNA that indicate to the enzyme ___________________ where to bind to make RNA.•What is the difference between exons and introns?• A codon consists of ______________________ nucleotides that specify a single amino acid that will be added to a polypeptide.•What is a polypeptide?• UCGCACGGU UCG-CAC-GGU (codes for) Serine-Histidine-Glycine• Ser, His, Gly are all amino acids. There are about 20 amino acids used by the human body. What do amino acids do?

RNA and Protein Synthesis• During the process of _____________, a cell uses information from messenger RNA to produce proteins.• If a messenger RNA (mRNA) strand codes for AUGUUC, what will the transfer RNA complimentary sequence read? Remember, in RNA, T is always replaced by uracil, U.• Study figure 12-19 on page 306 to solidify your understanding of how RNA and DNA operate. • So, during transcription, the DNA is “transcribed” by mRNA and the mRNA is complimentary to the template DNA.• Then, during translation, the mRNA is “translated” into peptides, polypeptides and proteins by the transfer RNA (tRNA) according which codons are present in the mRNA strand.

Mutations•When cells make mistakes during the copying and translation processes, this results in ____________.• ____________________ are changes in one or only a few nucleotides. These can be defined as substitutions, deletions or insertions.• Most mutations are ___________.• In some cases, however, mutations can be ____________ or ______________. • Mutations in most cells of the body affect only the individual such as _____________.• However, when mutations in ___________ occur, these mutations can be passed on to offspring.•What do you think the significance of mutation may be to living organisms?

Mutations

Gene Regulation•What is a group of genes that operate together?•What are promoter genes?•What are repressor genes?• How are genes “turned off” or “turned on”?• Generally, are operons found in eukaryotic cells?• Most eukaryotic genes are controlled individually and have _____________________ that are much more complex than those found in prokaryotic cells.• Cells don’t just grow and divide during embryonic development, they also undergo ________________. This means that they become specialized in _____________ and ______________.• For example, does a neural cell have the same structure as a skin cell? Do they have the same function? This is differentiation.

Gene Regulation

Chapter 12 Quiz• 1. When a unicellular organism passes a beneficial gene to an organism that does not have this beneficial gene, this is called what?• 2. What is a bacteriophage?• 3. What is the purpose of a protein coat on a bacteriophage?• 4. Name three scientists credited for discovering the structure of a DNA molecule.• 5. In a DNA strand, what are the four base pairs or nucleotides?• 6. In a DNA strand, how do these nucleotides hydrogen bond with each other?• 7. If a DNA strand has the nucleotide sequence TACGTT, what will its complimentary DNA strand sequence look like?• 8. What are histones?• 9. What are the three main differences between DNA and RNA?• 10. True/False. Most mutations are beneficial because they help species to adapt.

ANSWERS• 1. Transformation• 2. A virus that attacks bacterial cells• 3. To protect the virus’ genetic material• 4. Watson, Crick, Franklin• 5. A, T, C, G – adenine, thymine, cytosine, guanine• 6. A T & C G• 7. ATGCAA• 8. Proteins that allow a cell to ‘wrap up’ its DNA into chromatin• 9. RNA has ribose for a 5-Carbon sugar whereas DNA has deoxyribose; RNA is single stranded; RNA uses uracil in place of thymine as a nucleotide base pair• 10. False – most mutations are neutral and have no affect on the organism.