Cell Biology Chapter 16 Flashcards
Hereditary information is transmitted how? Genes consist of DNA that codes for what? The information in a cell’s DNA molecules undergoes what?
In the form of distinct units called genes; for functional products that are usually protein chains; replication to generate 2 copies for distribution into each daughter cell
Instructions stored in DNA are transmitted how? What is transcription? What is translation?
transmitted in a 2-stage process called transcription and translation; RNA is synthesized in an enzymatic reaction that copies information from DNA; the base sequence of RNA is used to direct the synthesis of a polypeptide (proteins)
Very long molecules of DNA must be fit into what? Bacterial chromosomes were once thought to be what?
the cell and, in the case of eukaryotes, into the nucleus; naked DNA
How is DNA packaged? What is the bacterial chromosome?
somewhat similarly to the chromosomes of eukaryotes; the main bacterial genome
The DNA molecule is bound to small amounts of what and localized to what? The bacterial DNA is what? The loops of bacterial DNA are held in place by what?
Amounts of protein and localized to a region of the bacterial cell called the nucleiod; supercoiled and folded into loops; held by RNAs and proteins
When is DNA converted into chromatin? At the time of division, the chromatin fibers condense into a more what? What are histones?
When bound to proteins; into more compact structure, the chromosome; Histones are a group of small basic proteins with high lysine and arginine content
Negatively charged DNA binds how and to what? The mass of histones in a chromosome is approximately equal to what? There are how many types of histones and explain?
stably to the positively charged proteins; to mass of the DNA; five, H1, H2A, H2B, H3, and H4
Chromatin contains what and present in about what? Chromatin contains a number of what?
equal numbers of all of these except H1, which is present in about half the amount of others; a number of nonhistone proteins which play a variety of roles
A Histone Octamer Forms what? Nucleosomes occur at what? Nucleosomes contain what?
Forms the Nucleosome Core; at 200-bp intervals; an octamer of 8 histones
Histone octamers contain what? Histone H1 is not a part of what? What is the core particle? What is a linker DNA? Histone H1 is thought to be associated with what?
2 H2A-H2B dimers and 2 H3-H4 dimers with the DNA wrapped around the octamer; the octamer; the octamer with DNA; Extra Dna; linker DNA found between core particles
Transcriptionally active DNA is packed how? What would a looser package allow?
is less tightly packed than inactive DNA; allow easy access by proteins involved in gene transcription
Cells can tightly regulate what? Each histone has a what?
the portions of chromatin that are active or inactive through altering histones; has a protruding tail that can be tagged by the addition of methyl, acetyl, phosphate, or groups
Histone tails can be what and the pattern of modification governs what?
be modified and the pattern of modification governs the activity of the nucleosomes/DNA
What is Acetylation, Deacetylation, and Methylation?
adds acetyl group to lysine of histone tails, relaxing chromatin; condenses chromatin by removing acetylated tails from histones; of histones can activate or repress expression depending on location/pattern; recruitment of other regulatory proteins
What is Heterochromatin? What is it not?
sections of chromatin so highly compacted that they show up as dark spots in micrographs; not expressed
