Chapter 5 cell bio

Base pair

Two complementary nucleotides in an RNA or a DNA molecule that are held together by hydrogen bonds´┐Żfor example, G with C, and A with T or U.

Cell cycle

The orderly sequence of events in which a cell duplicates in contents and divides into two

Centromere

Specialized DNA sequence that allows duplicated chromosomes to be separated during M phase

Chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope

chromatin remodeling complexes

enzyme that uses the energy of ATP hydrolysis to alter the arrangement of nucleosomes in eukaryotic chromosomes, changing the accessibility of the underlying DNA to other proteins, including those involved in transcription

Chromosome

A long threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Complementary

Describes two molecular surfaces that for together closely and form non covalent bonds with each other

deoxyribonucleic acid

DNA. A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins.

Double helix

two strands of nucleotides wound about each other; structure of DNA

Euchromatin

The less condensed form of eukaryotic chromatin that is available for transcription.

Gene

a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring.

Gene expression

process by which a gene produces its product and the product carries out its function

Genetic code

set of rules that specify to the codons in DNA or RNA that corresponds to the amino acids in proteins

Genome

All the genetic information in an organism; all of an organism's chromosomes.

Heterochromatin

Highly condensed region of an interphase chromosome; generally gene-poor and transcriptionally inactive

Histone

One small group of abundant highly conserved proteins around which DNA warp to form nucleosomes

histone modifying enzymes

Enzyme that catalyzes the covalent addition of a small molecule

Karyotype

An ordered display of the chromosome pairs of a cell arranged by size and shape.

Nucleolus

Large structure within the nucleus where ribosomal RNA is transcribed and ribosomal subunits are assembled

Nucleosome

Bead-like structure in eukaryotic chromatin, composed of a short length of DNA wrapped around a core of histone proteins

Replication origin

nucleotide sequence at which DNA replication is initiated

Telomere

repeating nucleotide at the ends of DNA molecules that do not form genes and help prevent the loss of genes

Life depends on what three things of genetic material?

1. Stable storage
2. Maintenance
3. Inheritance

What are the four nucleotides?

Adenine, Thymine, Guanine, Cytosine

What nucleotide is in RNA?

Uracil

What is a double helix composed of?

A pair of antiparallel, complementary DNA strands, which are held together by hydrogen bonds between G-C and A-T

Central Dogma of Biology

DNA-transcription-RNA-translation-protein

What happens when a gene is expressed?

Part of its nucleotide sequence is transcribed int RNA molecules, most of which are translated into proteins

How can a cell regulate its chromosomes structure?

By condensing and de condensing particular regions

When do chromosomes become visible?

during cell division

What are nucleotide subunits in DNA held together by?

Phosphodiester bonds

DNA has two grooves name them.

Major and minor

Two closely related species can have similar ______ but different _________.

Genome size and chromosomes

What microscope can see nucleosomes?

Electron microscope

Which chromosome is more compacted interphase or mitotic?

Mitotic

Nucleosomes are composed of

DNA tightly around histones

The pattern of modification of ______ tails can determine how a stretch of chromatin is handled by the cells.

Histone

The structure of chromatin varies along a ________ ___________ ___________.

Single interphase chromosome

What does heterochromatin specific histone modification do?

It allows heterochromatin to form and spread