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Chapter 7: Chromosome Structure
Chapter 7: Chromosome Structure Notecards
22
Biology
Undergraduate 3
10/16/2012

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Term
__________ size in different organisms range from a few thousand nucleotides in the smallest viruses to many billions of nucleotides in higher plants and animals.
Definition
1) Genome
Term
The units in which DNA size is expressed are __________ (thousands of bp) __________ (millions of base pairs) and __________ (billions of base pairs)
Definition
1) Kilobase (kb)
2) Megabase (Mb)
3) Gigabase (Gb)
Term
The human genome is __________ __________ in size.
Definition
1) 3 Gb
Term
The amount of DNA per haploid genome is called the __________-__________.
Definition
1) C-Value
Term
The __________-__________ __________ explains that even though there are large variations in the amount of DNA per genome, the number of genes does not vary much between related organisms.
Most of the increase in genome size comes from __________ or due to an increase in __________ __________-__________ DNA.
Definition
1) C-Value paradox
2) Polyploidy
3) Non protein-coding
Term
What are the three methods that are used to resolve the packaging problem?
Definition
1) Looping of DNA by attachment to a central protein scaffold
2) Supercoiling of loops using topiosomerase enzymes
3) Typing loops of DNA together using ring-shaped protein complexes (cohesins and condensins)
Term
The energy of __________ __________ is used by topoisomerase enzymes to introduce supercoils in DNA.
Definition
1) ATP hydrolysis
Term
__________ __________ is a combination of an endonuclease and DNA ligase.
It cuts both strands of a DNA duplex, passing another duplex through the gap while still holding the two cut ends and then seals the cut.
Definition
1) Topiosomerase II
Term
Upon breaking open a __________ cell, the DNA becomes unfolded into a sticky mess.
This is because the tight compaction of DNA requires the neutralization of a large number of __________ charges on the surface of DNA molecules. This is done by complexing with positively charged __________.
Upon cell lysis, these basic proteins become dilute and the DNA (called a __________ since it is not a true stable chromosome) becomes unfolded.
Addition of positively charged molecules during __________ __________ allowed for the isolation of intact bacterial nucleoids.
Definition
1) Bacterial
2) Negative
3) Proteins
4) Nucleoid
5) Cell lysis
Term
DNA in higher cells exist as a stable nucleo-protein filament called __________.
Definition
1) Chromatin
Term
Upon gentle lysis of nuclei, all of the DNA is seen as a beaded string structure.
The beads are called __________. Each bead consists of eight molecules of highly basic (__________ and __________ rich) proteins called __________.
Each nucleosome has a core made of two copies each of histones __________, __________, __________, and __________.
Definition
1) Nucleosomes
2) Arginine
3) Lysine
4) Histones
5) H2A
6) H2B
7) H3
8) H4
Term
In stained chromosomes, one can see a narrowing at one point - the __________.
With special staining techniques called __________ __________ more detail is visible.
In most cells in most organisms, the resolution of the light microscope is not sufficient to see a deletion of either single or even groups of genes; a special case occurs in the __________ __________ __________ of Drosophilia larvae. These are terminal tissues and are not passed onto the next developmental stage (the __________). In these specialized cells, the homologous chromosomes pair and undergo many rounds of __________ without strand separation or nuclear division.
Definition
1) Centromere
2) Chromosome banding
3) Salivary gland chromosome
4) Pupa
5) Reolication
Term
Each __________-__________ in the human chromosome represents 10 million base pairs worth of DNA.
Definition
1) G-band
Term
The salivary gland chromosomes have proved very useful in localizing closed genes by a technique called __________ __________ __________, where a labeled piece of DNA is hybridized to salivary gland chromosomes and the labeled band is located under the light microscope.
Definition
1) In situ hybridization
Term
The rate of DNA renaturation depends on what three factors?
Definition
1) Time
2) DNA concentration
3) Complexity of sequences in the DNA population
Term
__________ __________ __________ (__________ __________) are several different kind of sequences ranging from dinucleotide repeats to repeats of somewhat longer sequences which are not transcribed into __________ and often stay condensed even in __________ (heterochromatin.
A large fraction of these sequences are found near the centromeres (__________ __________) or near the ends of chromosomes (__________ __________).
Definition
1) Highly repeated sequences (satellite DNA)
2) mRNA
3) Interphase
4) Centromeric heterochromatin
5) Telomeric heterochromatin
Term
__________ __________ __________ are genes that are present in multiple copies (such as histones, tRNA and rRNA genes) as well as many functional complete transposons with intact transposase or reverse transcriptase genes.
Definition
1) Middle repeated sequences
Term
Most stained chromosomes show a lightly staining area that looks like a constriction; this is called the __________.
It has been known for a long time that when a chromosome breaks, only the part containing the __________ is partitioned properly at the cell division. The piece without a centromere (__________ __________) is usually lost within a few cell division cycles.
Definition
1) Centromere
2) Centromere
3) Acentric fragments
Term
The __________ is where the fibers of the spindle attach and pull the two daughter chromosomes to opposite spindle poles during the __________ stage of the cell division process.
Rarely, the centromere activity may diffuse and many spindle fibers may attach throughout the length of the chromosome - such chromosomes are called __________ and organisms with such are rare.
Definition
1) Centromere
2) Anaphase
3) Holocentric
Term
__________ centromeres are unusual in that they are quite small and have a well-conserved structure.
The three __________ __________ __________ within Yeast are usually followed by a 100-135 nucleotide variable sequence.
Attaching the centromere to any DNA sequence containing an origin of replication results in the creation of a stable __________.
Definition
1) Yeast
2) Centromere determining elements (CDE)
3) Minichromosome
Term
It has also been known for a long time that chromosomes, when broken by __________-__________, tend to have sticky ends that fuse with other broken chromosome ends.
The ends of chromosomes are unique in that they were named __________.
Definition
1) X-rays
2) Telomeres
Term
Since no known DNA polymerase can start a new chain, new DNA begins with __________ __________.
The two primers at the extreme __________-ends of linear chromosomes cannot be replaced by DNA.
If left un-repaired, the chromosomes would become progressively shorter as the cells replicate repeatedly, resulting in complete disappearance eventually.
Telomere repeats are generated by a special enzyme known as __________ that has an internal RNA template.
The shortening of telomeres is thought to be related to __________.
Definition
1) RNA primers
2) 5'
3) Telomerase
4) Aging
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