Exam 1 Terms List

Exam 1 Terms List - Exam 1 Terms List 1. DNA a....

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Exam 1 Terms List 1. DNA a. deoxyribonucleic acid; b. the genetic matieral; c. a double stranded structure, with each strand composed of repeating units of deoxyribonucletides 2. RNA – a. ribonucleic acid; b. a nucleic acid that is composed of ribonucleotides; c. in living cells, RNA is synthesized via the transcription of DNA 3. Griffith – performed an experiment that suggested that DNA is the genetic material using live and/or heat-killed strands of bacteria S. pneumoniae into mice and then made observations whether the mice died or not. He worked with two strands, IIIS (smooth, which secreted a smooth polysaccharide capsule) and IIR (rough, which did not). He found that the capsule is important in preventing the mouse’s immune system from inhibiting the proliferation of the bacteria. In dead mice he found many type IIIS (smooth) bateria , but when type IIR were injected, he found they did not cause a lethal infection. He then verified that the proliferation of smooth bacteria was responsible for causing the death of the mice when he killed the type IIIS bacteria with heat treatment before injecting them into the mice, which survived. He then mixed live type IIR bacteria with heat- killed type IIIS and injected them into mice, which killed the mice. He found after extracting the tissue that IIIS bacteria was found. Since type IIR cannot revert to type IIIS, he deduced that something from the dead IIIS was transforming the type IIR into IIIS. These experiments showed that some genetic material from the dead bacteria was being transferred to the living bacteria and providing them with a new trait. 4. Transforming principle – the identified substance that causes transformation to occur (e.g. type IIIS in the Griffth experiments). Acts a lot like genetic material. a. Information: genetic material must contain information necessary to conduct an entire organism (transformed bacteria acquired information to make a smooth capsule) b. Variation: significant amount of phenotypic variability occurs (capsule, vs. rough) c. Replication: since genetic material is passed from parent to offspring, and from mother to daughter cells during cell division, it must be copied d. Transmission: genetic material of smooth cell must be replicated so that it can be transmitted from mother to daughter cell during cell division 5. Avery, McLeod, McCarty – realized that Griffith’s observation could be used to identify the genetic material – “ What substances are being transferred from the dead smooth cell to the live rough cell?” a. They first prepared bacterial extracts from type IIIS strains containing each type of molecule i. Only one was able to convert the type IIR into type IIIS (the purified DNA)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
b. Then they treated samples of the DNA extract with enzymes that digest DNA (DNase), RNA (RNase) or protein (protease) c. When DNA extracts were treated with RNase or protease, they still converted type IIR bacteria into type IIIS i. These results indicate that contaminating RNA or protein in the
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 04/22/2008 for the course BIO 325 taught by Professor Saxena during the Spring '08 term at University of Texas.

Page1 / 20

Exam 1 Terms List - Exam 1 Terms List 1. DNA a....

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online