IB exam 2 Updated and Graded A+

describe the relationship between the genotype and phenotype of an organism - ANSWER the genotype (genes) determines the phenotype (physical traits/appearance) of an organism what is one single long and tightly condensed molecule of DNA? - ANSWER chromosome in a DNA sample, we find that 34% of the nitrogenous bases in the DNA is made up of Guanine (G). Predict the proportion of nucleotides in the genome contains Adenine (A). - ANSWER 16% explain how a cell can make a macromolecule such as a lipid from its glycerine and fatty acid subcomponents using the information that is stored in genes along a stretch of a DNA molecule. - ANSWER the DNA in cells codes for proteins. certain patterns of protein encode for certain molecules and appearances, which can produce molecules like lipids what is the central dogma of biology? - ANSWER DNA -> RNA -> protein what is a gene? - ANSWER a gene is a stretch of DNA that codes for a protein which strand of DNA gets transcribed into mRNA? - ANSWER the transcribed strand types of cause mutations - ANSWER substitution insertion/deletion (indel) types of effect mutations - ANSWER silent missense nonsense frameshift substitution - ANSWER one base is substituted for another insertion - ANSWER addition of one or more nucleotide pairs deletion - ANSWER a fragment of the chromosome is removed silent mutation - ANSWER a mutation that changes a single nucleotide, but does not change the amino acid created missense mutation - ANSWER a nucleotide-pair substitution that results in a codon that codes for a different amino acid nonsense mutation - ANSWER a mutation that changes an amino acid codon to a stop codon frameshift mutation - ANSWER mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide if a particular gene contains 300 bases along its sequence, how many amino acids will be strung together during protein synthesis? - ANSWER 100 if a protein has 150 amino acids, how many DNA nucleotides (bases) would make up that gene? - ANSWER 450 a protein has the following amino acid sequence. construct a DNA nucleotide sequence of this portion of the gene: phenylalanine-glycine-alanine-proline-valine-asparagine - ANSWER (this is just one possible answer due to genetic redundancy) AAA-CCC-CGG-GGG-CAA-TTG karyotype - ANSWER a picture of all the chromosomes in a cell why might a diploid organism have 2 homologous chromosomes, although each homologous chromosome may carry a different version (allele) of the gene from the copy that is carried by its homolog? - ANSWER a diploid organism inherited 1 homolog from 1 parent and the other from the other parent homologous chromosomes - ANSWER chromosomes that have the same sequence of genes and structure, and are paired during meiosis karyotype formula - ANSWER homologs of each type x number of types = total number of chromosomes (e.g. for humans, it's 2n=46) 2: two chromosomes per pair n: 23; 23 types of chromosomes 46: total chromosomes what does 4n=52 mean? - ANSWER 4: there are 4 chromosomes per group of chromosomes n: 13; there are 13 different types of chromosomes in this karyotype 52: total number of chromosomes what does 3n=6 mean? - ANSWER 3: there are 3 chromosomes per group of chromosomes n: 2; there are two different types of chromosomes 6: total number of chromosomes each cell in our body was produced from the original fertilized egg cell through mitotic cell divisions. what does that mean about the genetic information carried in each of the many cell types we have - ignoring mutations? - ANSWER every cell in our body (barring mutations) has exactly the same genetic information what feature of DNA allows for faithful copies to be made during DNA replication and passed on to the daughter cells? - ANSWER complementary base-pairing rules what model correctly represents the relationship between newly replicated and old DNA after DNA replication? - ANSWER semi-conservative replication why does S-phase have to precede mitosis? - ANSWER DNA has to be replicated before cell division chromosome - ANSWER a threadlike structure of nucleic acids and protein, carrying genetic information in the form of genes chromatid - ANSWER one half of a duplicated chromosome how many copies of a single autosomal gene do humans typically have in a cell during the G1 phase of the cell cycle? - ANSWER 2 explain how the steps of mitosis guarantee that the 2 daughter cells that are produced after cytokinesis are genetically identical copies of the original parent cell - ANSWER MITOSIS STEPS: prophase: DNA formed into chromosomes metaphase: chromosomes in the middle of the cell anaphase: chromosomes equally divided into two chromatids telophase: chromatids dissolve back into relaxed forms and then the cell performs cytokinesis since the chromosomes are divided evenly among both cells, and the chromosomes all contain the exact same DNA, the daughter cells are genetically identical copies of the original parent cell most of the genetic material of eukaryotes is located in the - ANSWER nucleus what is organized on linear pairs of chromosomes? - ANSWER the genome of the organism what consist of long, unbroken double-stranded molecules of DNA? - ANSWER chromosomes what's the sequence of nucleotide bases that carries genetic information to make proteins? - ANSWER DNA what links your genotype to your phenotype? - ANSWER the action of the proteins encoded by genes (links your genotype to your phenotype) a single, double-stranded molecule of DNA in the condensed state - ANSWER what does this structure represent on a molecular level? centromere - ANSWER the region of the chromosome that holds the two sister chromatids together during mitosis gene locus - ANSWER location of a gene on a chromosome sister chromatids - ANSWER replicated forms of a chromosome joined together by the centromere (the two chromatids on a single homolog) mitotic cell division (mitosis) - ANSWER 1. chromosomes are uncondensed in nucleus of cell 2. replicated chromosomes condense and nuclear envelope dissolves 3. spindle fibers attach to centromere and pull chromosomes to metaphase plate 4. sister chromatids separate and are pulled by spindle fibers toward poles of cell 5. nuclear envelope reforms, chromosomes decondense, and cytokinesis follows in Morse code, a series of two signal types (dots and dashes) code for 26 different letters of the alphabet. How is this analogous to the genetic code? - ANSWER the bases of DNA code for the more complex amino acid sequence of the proteins in cells transcribe the transcribed (template) strand of DNA into mRNA: CAATGGCTA - ANSWER GUUACCGAU DNA transcribed (template) strand 5'___3' DNA non-transcribed (sense) strand 3'___5' Given the locally unwound double strand above, in which direction does the RNA polymerase move while transcribing DNA? - ANSWER 3' to 5' along the transcribed (template) DNA strand what establishes the reading frame for an mRNA transcript? - ANSWER the first start codon encountered by ribosomes how will ribosomes translate this sequence into a polypeptide chain? 5'-UCUGAUGGGCUGAGUA-3' - ANSWER ----AUG-GGC-UGA---- AUG - methionine (start) GGC - glycine UGA - stop what is the amino acid sequence that corresponds to the following abbreviated DNA sequence? 5'-TATGAAAGT-3' non-transcribed 3'-ATACTTTCA-5' transcribed - ANSWER ATACTTTCA -> UAUGAAAGU -> Y E S different coat colors in mice phenotypes are directly caused by - ANSWER differences in protein amino acid sequence (while the genotype determines what traits are passed on, it is the proteins they code for that immediately affect an organism's phenotype) the phenotypic variation in the coat color trait in mice is passed from a parent to their offspring via _____. - ANSWER differences in DNA sequences in different parents what is true about mutations? - ANSWER mutations are the only source for the origin of new alleles both substitution and indel mutations could result in a non-sense mutation in the affected codon following the mutational event what is false about mutations? - ANSWER indel mutations that occurred in an exon (translated part of the gene) can be silent a substitution mutation can lead to a frameshift consider the wild-type DNA sequence: 3'-ATACTTTCA-5'. which of the following shows an indel mutation of the wild-type DNA sequence shown above that does NOT result in a frameshift mutation? a. ATA['']TTCA b. ATA[''']TCA c. ATTACTTTCA d. A[''']TTTCA - ANSWER b. ATA[''']TCA d. A[''']TTTCA transcribed strand: 3'-ATACTTTCA-5' write one of the possible DNA sequences of the transcribed strand that results from both a single substitution mutation of the first codon that would also cause a nonsense mutation - ANSWER ATACTTTCA -> ATTCTTTCA bacterial genome contains - ANSWER plasmids