TAKS Review DNA, Cell Growth and Genetics

Structure of DNA The structure of DNA is called a double helix, it looks like a twisted ladder DNA is made of repeating pieces called nucleotides Nucleotides are made of a 5-carbon sugar, a phosphate group, and a nitrogenous base

Structure of DNA There are four different nitrogenous bases in DNA. Only certain bases can bond. They pair to form the rungs of the ladder. Adenine Adenine bonds to Thymine Cytosine bonds to Guanine. The sides of the twisted ladder are made of alternating sugar and phosphates sugar phosphate sugar phosphate sugar phosphate sugar... TACG ¦¦¦¦ ATGC sugar phosphate sugar phosphate sugar phosphate sugar...

DNA Replication DNA makes an exact copy of itself using old strands as a template to make new strands.

Getting information from DNA DNA CONTAINS THE CODE TO MAKE PROTEINS DNA cannot leave the nucleus messenger RNA (mRNA) is a copy of the code that is used to make proteins on the ribosomes If even one nucleotide is missing or changed, the resulting mutation can alter the protein being produced

 Transcription uses DNA to make mRNA in the nucleus; mRNA leaves nucleus  Translation uses the mRNA, tRNA, rRNA and ribosomes to create a chain of amino acids that will become proteins.

What are some differences between DNA and RNA?

Practice Question If the template of a strand of DNA is 5’ AGATGCATC 3’, the complementary strand will be- A. 3’ TCTACGTAG 5’ B. 5’ CTACGTAGA 3’ C. 3’ AGATGCATC 5’ D. 5’ AGACGTCTA 3’ A

Practice Question In DNA, which of the following determines the traits of an organism? A. Amount of adenine B. Number of sugars C. Sequence of nitrogen bases D. Strength of hydrogen bonds C

Practice Question Which of the following is a change that could be passed on to an organism’s offspring? F Damage to the DNA of gamete cells G Damage to skin cells from exposure to sunlight H Damage to DNA in the cytoplasm of cheek cells J Damage to hair pigment cells with permanent dyes A

Practice Question A biologist collects DNA samples from 2 sisters. The younger sister has blond hair. The older sister has red hair. The sisters have different traits because their DNA contains different A. orders of nucleotides B. types of sugar molecules C. sized phosphate groups D. types of nitrogenous bases A

Practice Question “Thymine—guanine—thymine— cytosine” describes — F nucleotides within an RNA strand G a sequence of bases within a DNA section H points of DNA separation during protein synthesis J tRNA codons for specific amino acids G

Practice Question What process is occurring in the figure on the right? F RNA synthesis G Protein synthesis H Transcription J DNA Replication J

Practice Question If one nucleotide is omitted or accidentally repeated in the process of DNA replication, which of the following is most likely to occur? F Gene deletion G Gene mutation H Gene insertion J Gene segregation G

Practice Question Which of the following must occur before DNA replication can take place? A Translation of DNA into amino acids B Separation of the DNA molecule into codons C Transformation of DNA into RNA D Separation of the DNA double helix D

Practice Question This is a short section of mRNA. Which DNA code probably produced this section of mRNA? A 3' GCCTUT 5' B 5' GCCAUT 3' C 3' ATTGCC 5' D 5' GCCATA 3' D 3' CGGUAU 5'

Practice Question This illustration is an example of a normal DNA sequence. Which of the following represents a single base change in the sequence? D

Cell Growth As an organism grows their cells do not get bigger, they increase in number. Mitosis is the formation of two new daughter cells that are identical to each other and the original parent cell If mitosis is not controlled, cells multiply too quickly---this forms a tumor. Cancer is uncontrolled cell growth

How cells divide Interphase (longest phase) Metaphase Anaphase Telophase Cytokinesis Prophase Prometaphase Two new cells IDENTICAL to the parent cell

Meiosis Type of cell division by which germ cells (eggs and sperm) are produced. Involves a reduction in the amount of genetic material. Quick Vocabulary Review Eggs and sperm are called sex cells, germ cells or gametes

Genetics and Punnett Squares Genotypes are the genetic make up of organisms tt Genotype: TT, Tt, or tt Phenotypes are the physical characteristics short Phenotype: tall or short Homozygous would be TT or tt Heterozygous would be Tt

Try this: RrYy x RrYY RYRyrYry RY rY These are all the possible allelic combinations of RrYY

Check this: RrYy x RrYY RYRyrYry RYRRYYRRYyRrYYRrYy RY RRYYRRYyRrYYRrYy rY RrYy rrYYrrYy rYRrYYRrYyrrYYrrYy Remember capital letters are dominant, so lower case letters are… recessive

Practice Question If a cat has 38 chromosomes in each of its body cells, how many chromosomes will be in each daughter cell after mitosis? A. 11 B. 19 C. 38 D. 76 C

Practice Question If an organism has the genotype RrSsTtUu, what proportion of its gametes will be RSTU? A.1/2 B.1/4 C.1/8 D.1/16 D

Practice Question Two pea plants produce round seeds. Which of the following should you conclude about the genetic material in these two plants? A. They have identical DNA. B. They have the same parents. C. They grew from a single seed. D. They share a gene in common. D

Practice Question In guinea pigs, the allele for a rough coat (R) is dominant to the allele for a smooth coat (r). A heterozygous guinea pig is mated with a homozygous recessive guinea pig. Which of the following lists the genotypes that are likely for the offspring from this cross? A. 100% Rr B. 50% Rr and 50% rr C. 75% Rr and 25% rr D. 25% RR, 50% Rr, and 25% rr B

Practice Question If a plant that is homozygous tall and wrinkled is crossed with a short, wrinkled plant, which percentage of genotypes would most likely be found in the first- generation offspring? F 50% TTss, 50% ttSS G 100% TtSs H 100% Ttss J 50% TtSS, 50% ttSS H

Practice Question The information in the box identifies some of the organs of the kitten. Which of the following is identical for every cell in each of the four organs? A Amount of ATP B Function of cell C Size of cells D Genes in DNA C

Practice Question A deletion of a DNA base from a gene affects an organism by — F causing future gametes to have additional chromosomes G changing the sequence of amino acids in a protein H causing chromosome fragments to form long chains J changing the structure of ribose sugar in nucleic acids G