BIOL 1000 Lecture Notes - Lecture 30: Sister Chromatids, Chromatin, Centromere

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erinchimpanzee657

13 May 2017

School

University of Manitoba

Department

Biological Sciences

Course

BIOL 1000

Professor

Kevin G.Scott

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Document Summary

Almost all genes in a eukaryotic cell are found inside the nucleus (grouped into chromosomes) . Chromatin = diffuse mass of long, thin fibres, loose state of chromosomes . Composed of equal amounts of dna and protein molecules. Too thin to be seen with a microscope. Chromatin coils up as a cell prepares to divide, forming tight/distinct chromosomes . Each chromosome contains one long dna molecule (with hundreds of genes & proteins attached to. Eukaryotic chromosome has more complex structure than prokaryotic chromosome . Includes many more proteins to help maintain structure & control gene activity. Human body cells tend to have 46 chromosomes . Chromosomes are duplicated before they condense and divide . Tongue fern has more than 1200 chromosomes in every cell . Each chromosome will exist as 2 copies = sister chromatids (identical copy of dna molecule) .

Related Questions

The bacterium E. coli, which is a major model system for the study of genes and DNA, has a singular circular chromosome of about 4x106 bp. In contrast, human diploid cells have __1__ chromosomes, of __2__ different types (donât forget that the X Â¹ Y!). The total amount of DNA found in a haploid cell such as a sperm or egg is called the organismâs âC-valueâ; the human C-value is __3__.

Also in contrast to the E. coli circular chromosome is the fact that eukaryotic chromosomes are not circular, but instead are __4__. Eukaryotic chromosomes are complexed heavily with protein to form a DNA-protein complex generically called __5__. The proteins found can be considered to fall into two general classes: __6__ and __7__. The first class is made up of 5 major proteins called __8__, __9__, __10__, __11__, and __12__. On a weight to weight basis, these proteins make up about __13__% of the total mass of a chromosome. Since these proteins must associate relatively non-specifically with DNA, they are rich in the basic amino acids __13__ and __14__, which gives the proteins a net __15__ charge.

One goal of packaging the DNA into chromatin is to compact the genome so it will fit into a nucleus. The basic unit of chromatin structure is the __16__, which has __17__ base pairs of DNA wrapped around a âcore particleâ composed of __18__ copies each of the core histones. Each nucleosome is separated by a stretch of âlinkerâ DNA so that the repeating unit is approximately 200 bp. Lets do a little arithmetic: If we consider that the nucleosome is approximately __19__ nm in diameter, that there is about 200 bp in this structure, and that 200 bp of DNA would normally occupy __20__ nm if stretched out straight (recall that each base is spaced about 0.34 nm from the next), we can see that the nucleosome alone allows for a __21__-fold compaction ratio.

The nucleosome structure is further compacted by histone __22__, which is not a part of the core particle. Instead, this histone __23__ (does what?) to cause the nucleosomal 10 nm fiber to condense into a higher-order structure referred to as the __24__ nm fiber. In the nucleus, chromosomes do not just float around freely: they are tethered to a proteinaceous structure called the __25__ at specific DNA regions called âSARsâ, which stands for __26__. SARs are rich in topoisomerases, to allow the winding and unwinding of the DNA that accompanies replication and transcription to occur, despite this constraint.

The 30 nm fiber discussed above is the form in which transcriptionally active DNA is believed to exist in the nucleus; however, further condensation leads to a highly condensed inactive form called __27__; in this terminology, the active form is referred to as __28__. The inactive condensed form can be divided into two types: one type is essentially invariant between cell types, and since it is âon all t timeâ, it is referred to as __29__. The other type comes and goes, depending on the expression of the genes present in that region of the chromosome; it is referred to as __30__.

Eukaryotic chromosomes carry the genes, of course, but also have other functional regions. One such region is the place where the spindle apparatus attaches during mitosis and meiosis; this region of the chromosome is called the __31__. Another important part of the linear eukaryotic chromosome is the ends; these are called __32__. In humans, the end of each chromosome is composed of many repeats of the short sequence __33__. One more type of functional region on each chromosome is the place where DNA replication starts; in humans, each chromosome has several of these __34__. Thus, eukaryotic chromosomes carry several different types of functional sequences, which together allow for their __35__ during S phase, __36__ during mitosis and meiosis, and the __37__ of their genes

Chapter 6: How Cells Harvest Chemical Energy

What is the difference between photosynthesis and cellular respiration?

How do cells capture the energy released by cellular respiration?

What are the products of cellular respiration?

What does pyruvate do?

The conversion of CO2 and H2O into organic compounds using energy from light is called what?

If ATP accumulates in a cell, what happens?

A drug is tested in the laboratory and is found to create holes in both mitochondrial membranes. Scientists suspect that the drug will be harmful to human cells because the drug inhibits what?

As a result of glycolysis, there is a net gain of ________ ATP(s).

Which of the following is a result of glycolysis?

The enzymes of the citric acid cycle are located in what?

Chapter 7 Photosynthesis: Using Light to Make Food

What is the name given to organisms that can make their own food and thus sustain themselves without consuming organic molecules derived from other organisms?

What is an example of a photoautotroph?

What is the origin of chloroplasts?

In the chloroplast, sugars are made in a compartment that is filled with a thick fluid called what?

The oxygen released into the air as a product of photosynthesis comes from what?

What is the use and production of CO₂ in both photosynthesis and cellular respiration?

Know the parts of the chloroplast. Which structure in the chloroplast represents the thylakoid membrane?

What molecules are reactants of photosynthesis?

What is the source of energy that provides the boost for electrons during photosynthesis?

Why are most plants green?

Chapter 8: The Cellular Basis of Reproduction and Inheritance

What is called the creation of genetically identical offspring by a single parent, without the participation of sperm and egg?

How do eukaryotic chromosomes differ from prokaryotic chromosomes?

Prior to mitosis, each chromosome of a eukaryotic cell consists of a pair of identical structures are called what?

Eukaryotic cells spend most of their cell cycle in which phase?

What occurs during interphase?

What is the process called by which the cytoplasm of a eukaryotic cell divides to produce two cells?

What is the phase of mitosis during which the mitotic spindle begins to form?

During which phase of mitosis does the nuclear envelope re-form?

What feature of plant cell division distinguishes it from animal cell division?

What features likely accounts for the difference between plant and animal cell cytokinesis?

What must occur for a plant or animal to grow and develop normally?

Chapter 9: Patterns of Inheritance

Most genetic disorders of humans are caused by what type of alleles?

What is the difference between genotypes and phenotypes?

What are the individual features of all organisms?

What does the chromosome theory of inheritance state?

What is the normal complement of sex chromosomes in a human male?

The sex chromosome complement of a normal human female is what?

How many sex chromosomes are in a human gamete?

What is the gene located on a sex chromosome called?

Why are sex-linked conditions more common in men than in women?

Chapter 12: DNA Technology and Genomics

How long has Biotechnology been around?

What do restriction enzymes do?

What are "Sticky ends"?

What is the best definition of a genomic library?

What is a nucleic acid probe?

The only cells that can correctly attach sugars to proteins to form glycoprotein products are what?

How does a vaccine work?

What is the preferred name of the technique used to determine if DNA comes from a particular individual?

The polymerase chain reaction relies upon unusual, heat-resistant ________ that were isolated from bacteria living in hot springs.

Gel electrophoresis sorts DNA molecules on the basis of their what?

BIOL 1000 Lecture Notes - Lecture 30: Sister Chromatids, Chromatin, Centromere

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