Bio 184 Ch 10

What are some differences between the types of sequences found in eukaryotic chromosomes versus bacterial chromosomes?

-euks have centromeres and telomeres -euks have much more repetitive sequences

What are the important consequences of supercoiling?

-greatly decreases size of bacterial chromosome -negative supercoiling also affects DNA function

Chromosomes contain three types of regions that are required for chromosomal replication and segregation:

-origins of replication -centromeres -telomeres

To fulfill their role at the molecular level, chromosomal sequences facilitate four important processes:

1. synthesis of RNA and cellular proteins 2. replication of chromosomes 3. proper segregation of chromosomes 4. compaction of chromosomes so they can fit within living cells

Each eukaryotic chromosome contains many origins of replication that are interspersed about every _______ base pairs.

100,000

The chromosomes of eukaryotes typically contain: a. a few hundred to several thousand different genes b. multiple origins of replication c. a centromere d. telomeres at their ends e. all of the above

e

Genes are interspersed throughout the chromosomes. A typical eukaryotic chromosomes contains between _________ to ________ different genes.

few hundred, few thousand

Entire complement of genetic material in an organism or species.

genome

The non transcribed regions of DNA located between adjacent genes are termed _____ _____

intergenic regions

In more complex eukaryotes such as mammals and flowering plants, protein encoding genes tend to be much longer due to the presence of _______.

introns

The _______ is composed of a group of proteins that link the centromere to the spindle apparatus during mitosis and meiosis, ensuring the proper segregation of the chromosomes to each daughter cell.

kinetochore

Each chromosome contains a centromere that forms a recognition site for the ______ ______.

kinetochore proteins

Eukaryotic species have ______ chromosomes.

linear

A ______ ______ is a segment of DNA folded into a structure that resembles a loop.

loop domain

The chromosomal DNA in living bacteria is ________ supercoiled.

negatively

Define intron

noncoding intervening sequence

Inside a bacterial cell, a chromosome is highly compacted and found within a region of the cell known as a ______.

nucleoid

Eukaryotic species have how many sets of chromosomes in the cell nucleus?

one or more

One ______ ____ ______ is required to initiate DNA.

origin of replication

What holds the loop domains in place?

proteins hold the bacterial chromosomal loops in place

Define exon

regions of an RNA molecule that remain after splicing has removed introns

What does topoisomerase I do?

relaxes negative supercoils

Area of negative supercoiling on circular chromosome can cause...

strand separation

At the ends of linear chromosomes are found specialized regions known as

telomeres.

Each eukaryotic chromosome contains a long, linear DNA molecule that is typically how many base pairs in length?

tens to hundreds of millions

What does DNA gyros (topoisomerase II) do?

Contains four subunits (2 A and 2 B) introduces negative supercoils using energy from ATP.

Because the two strands within DNA already coil around each other, the formation of additional coils due to twisting force is referred to as

DNA supercoiling

Why is strand separation beneficial?

It's needed for certain processes such as DNA replication and RNA transcription

______ _____ _____ (also called structural genes) account for the majority of bacterial DNA.

Protein encoding genes

T/F: Bacterial chromosomal DNA is usually a circular molecule, though some bacteria have linear chromosomes

T

__________ contain specialized sequences located at both ends of the linear chromosome.

Telomeres

A typical chromosome is about how many base pairs in length?

a few million

Negative supercoiling may enhance activities like transcription and DNA replication because it: a. allows the binding of proteins to the major groove b. promotes DNA strand separation c. makes DNA more compact d. causes all of the above

b

________ are regions that play a role in the proper segregation of chromosomes during mitosis and meiosis.

centromeres

Repetitive sequences are commonly found near _______ and ______ regions, but they may also be interspersed throughout the chromosome.

centromeric, telomeric

Unlike the eukaryotic nucleus, the bacterial nuclei is not a separate cellular compartment surrounded by a membrane. Rather, the DNA in a nuclei is in direct contact with the ______ of the cell.

cytoplasm

A bacterial chromosome typically contains: a. a few thousand genes b. one origin of replication c. some repetitive sequences d. all of the above

d

DNA gyrase: a. promotes negative supercoiling b. relaxes positive supercoils c. cuts DNA strands as part of its function d. does all of the above

d

Mechanisms that make the bacterial chromosome more compact include: a. the formation of loop domains b. DNA supercoiling c. crossing over d. a & b

d

Eukaryotic chromosomes occur in sets. Many species are _______, which means somatic cells contain two sets of chromosomes.

diploid