TAKS review: DNA

Obj. 2 TEK 6 (A) describe components of deoxyribonucleic acid (DNA), and illustrate how information for specifying the traits of an organism is carried in the DNA; (B) explain replication, transcription, and translation using models of DNA and ribonucleic acid (RNA); (C) identify and illustrate how changes in DNA cause mutations and evaluate the significance of these changes; (D) compare genetic variations observed in plants and animals; TAKS Review

1. DNA is made up of thousands of units called nucleotides. What are the three parts of the nucleotide? Sugar, phosphate group, and nitrogen base 2. Which of these parts of the DNA stores genetic information? The sequence (order) of nitrogen bases. TEK 6(A) Adenine Guanine CytosineThymine There are 4 kinds of nitrogen bases in DNA: A, G, C, & T Phosphate group Deoxyribose

EXAMPLE A G T T C G G A might give you blue eyes, T G T C T A A G might give you brown eyes. The order of the nitrogen bases dictates the characteristics you have. The order dictates which proteins are made in your cells, and those proteins give you your traits.

TEK 6(B) 3. Nitrogen bases in DNA come in pairs. G bonds to ______ and A bonds to ______ G bonds to ______ and A bonds to ______ 4. If one side of the DNA is CAT TAC, then what would the complementary side of the DNA be? C T CAT TAC GTAAGT

An old TAKS question: Sickle-cell anemia is a disorder resulting from a mutation that leads to the production of an abnormal protein. Which component of the DNA molecule provides instructions for the production of the protein? Sickle-cell anemia is a disorder resulting from a mutation that leads to the production of an abnormal protein. Which component of the DNA molecule provides instructions for the production of the protein? A The phosphate groups A The phosphate groups B The sugar molecules B The sugar molecules C The sequence of nitrogen bases C The sequence of nitrogen bases D The bonds that hold the sugars to the bases D The bonds that hold the sugars to the bases

And another… In all plant and animal cells, the nucleus contains long molecules of DNA. Which of the following best describes the function of DNA? F DNA provides the shape and structure of the nucleus. G DNA packages materials for transport through the nucleus. H DNA carries materials into and out of the nucleus. J DNA contains the blueprint for producing the whole organism.

And another… If the template of a strand of DNA is 5' AGATGCATC 3', the complementary strand will be — If the template of a strand of DNA is 5' AGATGCATC 3', the complementary strand will be — F 3' TCTACGTAG 5‘ G 5' CTACGTAGA 3‘ H 3' AGATGCATC 5‘ J 5' AGACGTCTA 3' J 5' AGACGTCTA 3'

And even one more: Erwin Chargaff studied the DNA of organisms within a single species. Chargaff discovered that the amount of adenine is about equal to the amount of thymine. Which of these explains why the ratio of adenine to thymine is nearly 1:1? A Adenine and thymine pair with each other. B Adenine binds with phosphates, while thymine binds with nitrates. C Adenine and thymine are identical in chemical composition. D Adenine bases contain a form of thymine.

One more… The sequence of amino acids coded by a strand of DNA directs the cell to make specific A. Carbohydrates B. Lipids C. Proteins D. Vitamins

DNA replication

5. What happens just before a cell divides? DNA replication occurs so that each new cell can have an exact copy of DNA. (Note: Body cells divide in mitosis to create two identical cells that have identical DNA and the same number of chromosomes.) TEK 6(B)

Think of the replicator on Star Trek: replication means copying.

TAKS question… If a cat has 38 chromosomes in each of its body cells, how many chromosomes will be in each daughter cell after mitosis? If a cat has 38 chromosomes in each of its body cells, how many chromosomes will be in each daughter cell after mitosis? F 11 G 19 H 38 J 76 J 76

Making Proteins Review: In what part of the cell are proteins made? Where are the instructions for making those proteins? There are two steps in making proteins: transcription and translation

DNA transcription

DNA contains the instructions to make proteins. Unfortunately, the instructions are in another language, and the workers that will actually make the proteins don’t understand it. That’s where mRNA comes in – it will provide the directions in a language the workers can understand.

DNA transcription In transcription, the DNA is unzipped, and mRNA is transcribed. The instructions for making proteins are written into the mRNA. Think of a prescription: the doctor’s orders are written down. “script” means something written down.

6. Which nitrogen bases in found in RNA but not in DNA? Uracil –U (A bonds to U in RNA) 7. What would the mRNA codon be that would be created from the DNA sequence: CAT TAC? TEK 6(B) CAT TAC GUAAGU DNA- mRNA-

nucleus RNA Polymerase 8. What is the process of copying the genetic information in DNA to mRNA called? Transcription TEK 6(B) What: Copies DNA to make mRNA Where: In the nucleus Why: to carry instructions out of nucleus DNA mRNA Nucleus

DNA translation After the mRNA brings the instructions from the nucleus to the site of protein production, the protein is assembled during translation.

9. mRNA contains information on what order to put amino acids together to form a ______________ chain during the process of translation. 10. The codon AUG codes for which amino acid? TEK 6(B) Protein AUG= methionine

Let’s practice making a protein… /transcribe/

Practice question: A cell with numerous ribosomes is probably specialized for— A. enzyme storage B. energy production C. protein synthesis D. cell division

11. What is a mutation? is a change in genetic material (Change in DNA leads to changes in protein chain.) TEK 6(C) DNA- mRNA- Amino Acid chain (Protein)- Mutation in one DNA base Causes changes in one mRNA base New codon codes for a different amino acid

Sample TAKS question: A mutation is defined as: A. a change in an organism's DNA B. the growth of an abnormal cell structure C. the changing of a cell from one type to another D. a way of changing mRNA to proteins

Question: The molecule which acts as an intermediary between the DNA and the ribosomes is A. messenger RNA B. transfer RNA C. ribosomal RNA D. intermediate RNA

TAKS question: Mutations in DNA molecules can occur when — F. replication of DNA is exact G. a DNA enzyme attaches to an RNA codon H. RNA codons are replaced by DNA nucleotides J. a change occurs in DNA nucleotide bases

Genotype: genetic make-up of an organism ex. Bb Phenotype: expression of the genes of an organism (ex. BLACK hair.) Dominant: trait that is always expressed Recessive: trait that can be hidden in the presence of a dominant gene. Gene: segment of DNA that codes for a protein that controls a trait. Trait: inheritable characteristic TEK 6(D) Genetics Vocabulary Review