Lecture_16_-_Chromosome_Structure_and_DNA_Sequence_Organization

Lecture_16_-_Chromosome_Structure_and_DNA_Sequence_Organization

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon

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

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Lecture 16 Lecture 16 Chromosome Chromosome Structures Structures Chromosome Structures Chromosome Structures • The manner in which DNA is organized in different species is related to how the ‘genes’ that occur on the DNA are stored, expressed and transmitted from one generation to the next in a species. • For example, eukaryotic chromosomes are made up of DNA molecules complexed with various protein molecules in a structure called chromatin • Prokaryotic chromosomes found in viruses and bacteria are largely devoid of any associated proteins Viral Chromosomes Viral Chromosomes • Viral chromosomes can be either single stranded RNA molecules, single stranded DNA molecules or double stranded DNA molecules • Some viral chromosomes exist as linear structures and some exist as looped circular structures • Some viral chromosomes have double stranded linear structures which close to form a circular ring when they infect a host cell; while some occur in linear form and remain in linear form even after they infect a host cell Viral Chromosomes Viral Chromosomes • One constant feature shared by viral, bacterial and eukaryotic cells is their ability to package long DNA (or RNA) molecules into a relatively small volume • For example, the DNA of the bacteriophage lambda ( λ ) is 17 μ m long and must fit into the phage head which is less than 0.1 μ m on any side • In many cases, almost all the space in the head is filled, indicating nearly perfect packaging • Once packaged, the DNA is functionally inert until released into a host cell Bacterial Chromosomes Bacterial Chromosomes • Bacterial chromosomes are always double stranded DNA compacted into a structure sometimes called a nucleiod • Bacterial chromosomes are usually large circular structures that in many cases occupy a large volume of the cell • Bacterial chromosomes, unlike viral chromosomes, contain several types of small DNA-binding proteins • Also unlike the tightly packed viral chromosomes, bacterial chromosomes are fully functional and can be replicated and transcribed Mitochondria and Mitochondria and Chloroplasts Chloroplasts • Mitochondria are cytoplasmic organelles found in animal species that are heavily involved in energy production for the cell through the process of aerobic respiration • Chloroplasts are similar structures found in plants that perform a similar function by converting the energy in sunlight into stored energy which is used in cell metabolism and growth (photosynthesis) Mitochondria and Mitochondria and Chloroplasts Chloroplasts • Both mitochondria and chloroplasts contain their own DNA which is separate from the nuclear DNA found in the cell • Both these cytoplasmic organelles contain their own mechanisms for replicating and expressing traits controlled by genes located on this extranuclear DNA • These traits are transmitted via the cell cytoplasm rather than through the DNA found in the nucleus of the cell Mitochondria and Mitochondria and...
View Full Document

This note was uploaded on 05/07/2011 for the course DARY 2072 taught by Professor Hay during the Spring '09 term at LSU.

Page1 / 49

Lecture_16_-_Chromosome_Structure_and_DNA_Sequence_Organization

This preview shows document pages 1 - 9. Sign up to view the full document.

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