Biology 1320 Exam 3 Bergh Questions With Correct Solutions, Already Passed!!

RNA nucleotide base pairings - Cytosine (C) pairs to Guanine (G) Adenine (A) pairs to Uracil (U) DNA Sructure - because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand Griffith's Experiment - in the 1920's, Frederick Griffith worked with two strains of Streptococcus pneumoniae bacteria. It was discovered that DNA was transmitted between the toxic and the harmless bacteria. DNA - -deoxyribonucleic acid -stores the information that the cell needs to produce proteins transciption - the gene's sequence is copied from DNA to a middleman molecule called mRNA translation - the gene's sequence is now encoded in mRNA, which directs the production of a protein Bacterial Transformation - DNA fragments are transported into the bacterium -- A DNA fragment is incorporated into the chromosome DNA Structure is a.... - Double helix DNA Backbone - Hydrogen bonds connect complementary DNA strands; Opposite ends of the strand are designated 5' and 3'. Strands oriented in different directions DNA is composed of - nucleotidesNucleotides - the phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the "rungs". There are four types of nitrogenous bases. Nucleotide binding in DNA - Adenine (A) binds to Thymine (T) Guanine (G) binds to Cytosine (C) Protein Production starts with... - DNA A _____ is a sequence of DNA that encodes a specific protein - gene Protein production occurs in 2 stages: - transcription and translation RNA structure is... - single stranded DNA function - stores RNA- and protein- encoding information; transfers information to next generation of cells RNA function - carries protein-encoding information; helps to make proteins; catalyzes some reactions Three types of RNA interact to produce proteins (transcription) - -Messenger RNA (mRNA) -Ribosomal RNA (rRNA) -Transfer RNA (tRNA) How does DNA pair with RNA? - DNA -- RNA A -- U C -- G G -- CT -- A Transcription Steps - Initiation, Elongation, Termination Initiation of Transcription - RNA polymerase binds to the promoter, which is the beginning of the gene Elongation in Transcription - RNA polymerase moves along the template strand, making an RNA copy. Notice that the RNA molecule is complementary to the DNA template strand. Termination of Transciption - RNA, DNA, and RNA polymerase separate. DNA becomes a double helix again What are the three components of a nucleotide and, in a DNA helix, what parts are facing the interior and which are facing the exterior? - Phosphate group, Sugar (deoxyribose), Nitrogenous Base. Phosphate and sugar form the backbone facing outward while the bases face the interior. There are three major classes of RNA molecules produced. What are they and what are their functions? - mRNA: Messenger RNA transcribes the genetic code form DNA into a form that can be read and used to make proteins. mRNA carries genetic information from the nuclei to the cytoplasm of a cell. rRNA: Ribosomal RNA is located in the cytoplasm of a cell, where ribosomes are found. rRNA directs the translation of mRNA into proteins. tRNA: Transfer RNA is located in the cellular cytoplasm and is involved in protein synthesis. it brings or transfers amino acids to the ribosome that correspond to each three-nucleotide codon of rRNA. The amino acids then can be joined together and processed to make polypeptides and proteins. Describe the process of translation, in detail. (AND BE SURE YOU KNOW HOW IT DIFFERES FROM TRNSCRIPTION)o What occurs during initiation? Including pre-initiation complex, then binding of mRNA, followed by attachment of large ribosome complex. o What occurs during elongation? Include the function of the second tRNA, the catalytic site, the attachment of the free amino acids, shifting to the next codon, etc. o What occurs at termination? What determines an ending point to translation? - InitiationtRNA with an attached methionine bind to small ribosomal subunit forming the preinitiation complex.Pre-initiation complex binds to mRNA and the methionine binds with the start codon on the mRNA Large ribosomal subunit now binds to smaller one. Methionine tRNA binds to 1st tRNA site on large ribosomal unit o Elongation Amino acids are added one at a time to the protein chain Catalytic site forms a peptide bond between the 2 amino acids now attached to the tRNA 1st tRNA releases and ribosome moves one codon over to the right o termination elongation repeats until a stop codon is reached; mRNA and completed peptide are released from the ribosome Describe the mechanisms that eukaryotes can regulate gene expression. - o 1. Cells can control frequency of transcription of individual genes o 2. Same gene may be used to produce diff mRNAs and protein products- differential splicing of exons make different proteins o 3. Cells control stability and translation of mRNAs - some tRNAs are long lasting and some may not be o 4. Proteins require modifications before they carry out their functions. -modificaitons may include taking out certain parts o 5. Cells control protein degredation rates. - can regulate by deciding which protein it wants more of Cell division is the process of dividing a parent cell into two identical daughter cells. How is the process different in sexual versus asexual reproduction? - In sexual, the daughter cell is coming from two different parents. In asexual, the daughter cell is coming from 1 parent and is a clone. Define a clone? - offspring genetically identical to the parent and to each other. What is apoptosis and how is it different from cell division? - cell death. Mitosis adds new cells while apoptosis removes them, allowing tissues to renew themselves. What is the first step in all cell division processes? - Interphase- stage where the chromosome replicate and the cell growsBe able to explain the process of binary fission. - 1. Parent cell contains one chromosome 2. DNA replicates and attaches to cell membrane 3. Membrane growth between the 2 attatchment points moves the DNA molecules apart as new cell wall material is deposited 4. The result of this is two daughter cells, each identical to the original.