Chapter 11

DNA helicase

An enzyme that unwinds the DNA double helix during DNA replication

nuclear matrix

A filamentous network of proteins in the nucleus and lines the inner membrane

radial loop domains

A loop of chromatin, often 25,000 to 200,000 base pairs in size, that is anchored to the nuclear matrix.

purines have double ring ex adenine , guanine pyrimidines have single ring ex cytosine, uracil, thymine

Five different bases are found in nucleotides, although any given nucleotide contains only one base. The five bases are subdivided into two categories, the purines and the pyrimidines, due to differences in their structures (see Figure 11.4). The purine bases, adenine (A) and guanine (G), have a double-ring structure, whereas the pyrimidine bases, thymine (T), cytosine (C), and uracil (U), have a single-ring structure. Adenine, guanine, and cytosine are found in both DNA and RNA. Thymine is found only in DNA, whereas uracil is found only in RNA.

DNA carries the genetic instructions for the characteristics of living organisms. In the case of multicellular organisms such as plants and animals, the information stored in the genetic material enables a fertilized egg to develop into an embryo and eventually into an adult organism. In addition, the genetic material allows organisms to survive in their native environments.

For example, an individual's DNA provides the blueprint to produce enzymes that are needed to metabolize nutrients in food. To fulfill its role, the genetic material must meet the following key criteria: Information: The genetic material must contain the information necessary to construct an entire organism. Replication: The genetic material must be accurately copied. Transmission: After it is replicated, the genetic material can be passed from parent to offspring. It also must be passed from cell to cell during the process of cell division. Variation: Differences in the genetic material must account for the known variation within each species and among different species.

During DNA replication, the lagging strand is synthesized as a series of small fragments called ___________ fragments

Okazaki

major grooves

Segments of the DNA double helix in which proteins can bind to specific DNA sequences. These are very big spaces, and very information-rich, affects gene expression

histones

The first way DNA is compacted is by wrapping itself around a group of proteins

backbone

The linear arrangement of phosphates and sugar molecules in a DNA or RNA strand.

nuclear lamina

a collection of filamentous proteins that line the inner nuclear membrane; part of the nuclear matrix

chromosome

a discrete unit of genetic material composed of DNA and associated proteins. Eukaryotes have chromosomes in their cell nuclei and in plastids and in mitochondria

nucleosome

a structural unit of a eukaryotic chromosome, composed of octamer of histone (8 histone protein) wrapped with DNA.

Transformation

a type of genetic transfer in bacteria in which a segment of DNA is taken up by a competent cell and incorporated into the bacterial chromosome.

genome

all of an organism's genetic material

DNA topoisomerase

an enzyme that alleviates DNA supercoiling during DNA replication

Telomerase

and enzyme that catalyzes the replication of the telomere prevents chromosome shortening by attaching many copies of a DNA repeat sequence to the ends of chromosomes

DNA ligase

catalyzes the formation of a covalent bond between these two DNA fragments to complete the replication process in the lagging strand

Hetrochromatin

describe the highly compacted regions of chromosomes.

a chromosome is composed of

dna and proteins

In the Avery, McCarthy, McLeod experiment results

dna is the genetic component

a nucleosome is composed of ________________ wrapped around a octamer of histone proteins

double stranded DNA

Protease

enzyme that cut proteins into smaller polypeptides

DNase

enzyme that digests DNA

RNase

enzymes that digest RNA

the less condensed regions of chromosomes are referred to as

euchromatin

linker regions of DNA are sequence that

exist between adjacent nucleosome. A particular histone called H1 is bound to this linker region

DNA is compacted by wrapping itself around a group of protein called

histones

Directionality

in DNA and RNA strand, refers to the orientation of the sugar molecules in the strand. can be 5' to 3' or 3' to 5'

deoxynucleoside triphosphates

individual nucleotides with three phosphate groups

DNA polymerase

is responsible for covalently linking nucleotides together to form DNA strands.

chromatin

is used to describe the complex of DNA and protein that makes up eukaryotic chromosomes.

nucleosomes are connected by __________ regions of DNA that vary in length from 20 to 100 base pairs depending on species and cell type.

linker

the nuclear ____________ consists of nuclear lamina made of protein fibers and other protein that are connected to the lamina and fill the interior of the nucleus

matrix

A metaphase chromosome is _____________ a chromosome in a non dividing cells

more condensed than

griffith work performed at a time when the transforming substance was

not known

the 30 nm of fiber of chromatin can be further compacted by forming radial loop domains that are anchored to the

nuclear matrix

The 30 nm fiber is comprised of ___________________ units organized in a more compact structure

nucleosome

The repeating structural unit of eukaryotic chromatin is the

nucleosome

30 nm fiber

nucleosome units organized into a more compact structure that is 30 nm in diameter

The structure of connected _____________ can be likened to beads on as string

nucleosomes

the negative charges found in the ___________ group of DNA is attracted to positive charges on ___________ proteins found on chromatin

phosphate histone

in order to ensure speed, fidelity, completeness during DNA replication nearly all living species

produce more than one type of polymerase

phosphodiester bond

refers to double linkage, (2 phosphodiester bond) that hold together adjacent nucleotides in RNA and DNA

heterochromatin

refers to highly compacted regions

Heterochromatin

refers to the compaction level of the molecule

Telomere

repetitive DNA at the end of a eukaryotic chromosome

leading strand

synthesized continuously

lagging strand

synthesized in smaller fragments that are later connected

This is a region at the end of eukaryotic chromosomes

telomere

Proofreading

the ability of DNA polymerase to identify a mismatched nucleotide and remove it from the daughter strand

replication fork

the are where two DNA strands have separated and new strands are being synthesize

Euchromatin

the less condensed regions; areas that are capable of gene transcription

bidirectional

the process in which DNA replication proceeds outwards from the origin in opposite direction

minor grove

the smaller groove that spiral around the DNA

base pairs

the structure in which 2 bases in opposite strand of DNA hydrogen bonds with eachother

the formation of nucleosomes and their arrangements in 30 nm are important because _________

they compact DNA