32. Cell Cycle Events Interphase Cell Division Longest phase of the cell cycle. DNA is in chromatin form G1- Growth (organelles duplicate) S- replication (duplication) or DNA G2- Cell Growth Prophase- chromosomes Metaphase- Chromosomes align along the metaphase plate (middle) Anaphase- sister chromatids separate Telophase- Cleavage furrow begins and nuclear envelopes reform. Cytokinesis- division of the cytoplasm (two new cells)

33. If a skin cell had 52 chromosomes, how many chromosomes would be found in an egg cell? 26

34.) Compare and contrast mitosis and meiosis ds ds Only once through division cycle Goes through division cycle twice Go through interphase (cell growth) majority of time At anaphase 1, Homologous chromosomes separate At anaphase, sister chromatids separate Go through PMAT (second division of meiosis is similar to mitosis) At cytokinesis, two identical cells separate At cytokinesis 1, two haploid daughter cells are formed Chromosome # is identical as the original cell Chromsosome # is half of the original cell and a UNIQUE combination TWO IDENTICAL DIPLOID CELLS Makes BODY (somatic) cells FOUR UNIQUE HAPLOID CELLS Makes GAMETES (egg and sperm)

35. Non-disjunction Nondisjunction is the failure for duplicated chromosomes to separate Generally during Meiosis II Down syndrome is also known as TRISOMY 21. Three copies of the 21st chromosome

36. Describe the shape and composition of a DNA molecule Shape: Double Helix Composition: Phosphate group Deoxyribose sugar 1 of 4 nitrogen bases http://ghr.nlm.nih.gov/handbook/basics/dna

37. What is the function of DNA? The function of DNA is to store heredity information that will be passed down to generations. It also contains the code for generating mRNA; this will eventually lead to tRNA, rRNA, and eventually proteins.

38) Base Pairing A-T (adenine to thymine) C-G (cytosine to guanine) Bonded by hydrogen bonds 2 bonds between A and T 3 bonds between C and G

39) DNA vs. RNA DNA RNA A,T,C,G Deoxyribose sugar Double helix More complex A,U,C,G Ribose sugar Single Strand Less complex

40) Codons Set of three nucleotides on the mRNA strand Instructions for amino acids which then leads to protein production Codes for amino acids 3 letters make up a codon

41) mRNA sequence mRNA: UUC GUU GGA ACC DNA: AAG CAA CCT TGG Amino acid: Phe-Val-Gly-Thr

42 a. Point Mutations Substitution Point where one nitrogen base is substituted for another Sickle Cell Anemia: substitute A for T

42 b. Frame Shift Mutations Deletions and Insertions When a nitrogen base is deleted or added Frame shift mutations- because it moves the codon up or down Changes the sequence of amino acids after the mutation

43) Transcription vs. Translation DNA to RNA Occurs in nucleus RNA to protein Occurs in cytoplasm

44.) Define the following terms: Genotype: The genetic makeup of an organism Phenotype: The physical traits of an organism Homozygous: Having two identical alleles for a given gene Heterozygous: Having two different alleles for a given gene Dominant: In a heterozygote, the allele that determines the phenotype with respect to a particular gene (the larger letter) Recessive: In a heterozygous individual, the allele that has no noticeable effect on the phenotype (the smaller letter)

45. How are the following words related? DNA, gene, RNA, protein, trait Gene (stretch of DNA) that is transcribed into RNA, that is translated into PROTEIN, that is expressed as a TRAIT

46. Punnett Square tool used to determine the probability of traits being passed on to offspring based on parents genotypes Parents genotypes represent egg and sperm Offspring's genotypes represent body cells

47. a)Monohybrid Heterozygote Parents (Tt x Tt) b) Blonde hair is dominant to brown. Two parents are mated one with blonde hair and one with brown, and some of their children end up with blonde and some with brown. a) b) Parent 1- Bb Parent 2- bb

48. Children born with a recessive genetic disorder can have parents that do not express the disorder, because the parents are heterozygous. The parents have the gene for the disorder, but it is masked by the dominant gene. This is how some traits can “skip” a generation.

49. Gene Pool Gene pool is the available genes in a breeding population.

50. Species can achieve genetic variation over many generations by breeding outside of the immediate family. No inbreeding This allows new genes to be introduced

51. A species can loose genetic diversity overtime by not “adding” to the gene pool. Inbreeding No gene shuffling