Molecular Text 4.1
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__ is passed on from a cell to its daughter cells at __, and between generations through __, which are stored as __, the information-containing elements that determine the characteristics of a species as a whole and of the individual within it
Genetic info consists mostly of __
Hereditary info is carried on __, threadlike structures in the nucleus of a eukaryotic cell that become visible by LM as cells divide; they have both __ and __
- Hereditary information
- cell division
- instructions for making proteins
- DNA and proteins
Pacing of DNA is done orderly so that the what
, as well as what?
chromosomes can be replicated and apportioned correctly between the two daughter cell at each cell division
allow access to chromosomal DNA for enzyme to repair damage
DNA is a __ with __ as determined by x-ray diffraction, which determined that DNA was composed of __ of the polymer wound into a __
A DNA molecule has __ composed of four types of __, called __ or __; and, they are held by hydrogen bonds between the nucleotides.
- long polymer
- four subunits
- two strands
- two long polynucleotide chain
- nucleotide subunits
- DNA strands or chain
The sugar is __ attached to a __ with either __(4)__
The nucleotides are __ together in a chain to form a backbone of alaternating __
five-carbon sugar and a phosphate group, as well as nitrogen-containing base
single phosphate with either A, C, G, or T
- covalently linked
DNA has __; it goes from a __direction.
All bases are __the double helix, and the sugar-phosphate backbones are __; a __(bulkier two-ring base) is paired with a __(single-ring base)
This complementary base-pairing allows what?
- chemical polarity
- base pairs to be packed in the energetically most favorable arrangement in the interior of the double helix
To maximize the efficiency of __, the two sugar-phosphate backbones do what?
Strands must be __; and, as a result, each strand contains a sequence of nucleotide that is exactly __to the nucleotide sequence of its partner strand
- base-pair packing
- wind around each other to form a double helix, with one complete turn every ten base pairs
DNA encodes information through the __ of the nucleotides along each strand.
Differences arise from different __--> different biological messages
Nucleotide sequences, via __, can convert into the __, and then into the __
- order, or sequence
- nucleotide sequences
- gene expression
- sequence of RNA
- amino acid sequence
The complete set of information in an organism’s DNA is called its __, and it carries the information for all the __ and __ that the organism will ever synthesize
During cell division, the cell must do what?
This is done how?
This enables a cell to do what
before pasing it on to its descendant.
- proteins and RNA molecules
- copy its genome to pass it to both daughter cell
as a single DNA strand acts as a template to synthesize the complementary strand
copy, or replicate, its genome
The DNA is enclosed in a __, which is 10% of the total cell volume; the compartment is delimited by a __ formed by __, which have __, which do what?
The envelope is connected to the __and is mechanically supported by a network of __ called the __, which forms a thin sheetlike meshwork just beneath the inner nuclear membrane.
- nuclear envelope
- two concentric lipid bilayer membranes
- nuclear pores
- transport molecules between the nucleus and the cytosol
- intermediate filaments
- nuclear lamina
The nuclear envelope allows what two things?
__establishes an environment in which __ are facilitated by the __ and __; it also prevents __
- 1) the many proteins that act on DNA to be concentrated where they are needed in the cell
- 2) keeps nuclear and cytosolic enzymes separate, a feature that is crucial to proper functioning
- biochemical reactions
- high concentration of both substrates and the enzymes that act on them
- interference from other enzymes
The most important function of DNA is to __, the info that specifies all the proteins and RNA molecules that make up an organism—including information about when, in what types of cells, and in what quantity each protein is to be made
Genomes are divided into __
Specialized proteins bind to and fold the __, generating a series of __ and __ that provide __, preventing the DNA from becoming tangled
coils and loops
increasingly higher levels of organization
In eukaryote, the DNA in the nucleus is divided between a __
Each chromosome consist of a __associated with __ that __ and __ the fine DNA thread into a more compact structure.
This complex of DNA and protein is called __.
Chromosomes are also associated with many __ and __ required for the proceses of __, __, and __
- set of different chromosomes
- single, enormously long linear DNA molecule
- fold and pack
- proteins and RNA molecule
- gene expression, DNA replication, and DNA repair
Each human cell (except __ and some highly specialized cell types) has __. The __ and __ of a pair are __
The only __ are the __ in males, where a __ chromosome is inherited from the father and a __chromosome from the mother
Each human cell has __chromosomes
- germ cell
- two copies of each chromosome, one from each parent
- maternal and paternal chromosomes
- homologous chromosomes (homologs)
nonhomologous chromosome pairs
__ is a technique in which a __serves as a “__” that localizes a __; can be used to distinguish these human chromosomes by painting each one a different color
The display of the __ at mitosis is called the human __. If parts of chromosomes are lost or are switched between chromosomes, these changes can be detected by changes in the __ or by changes in the pattern of chromosome painting
- DNA hybridization
- labeled nucleic acid strand
- complementary strand
- 46 human chromosomes
- banding patterns
Chromosomes carry __—the functional units of heredity.
A gene is usually defined as a __
Several percent of genes, however, produce an __, instead of a protein, as their final product
Like proteins, these RNA molecules perform a diverse set of __ and __ in the cell
- segment of DNA that contains the instructions for making a particular protein
- RNA molecule
- structural and catalytic functions
The complete nucleotide sequence of their genomes reveals that the DNA molecule that make up their chromosome are little more than __
Chromosomes from many eucaryotes contain, in addition to genes, a large excess of __
Sometimes called “__” to signify that __, the particular nucleotide sequence of most of this DNA may not be important. Some, however, is crucial for __
- strings of closely packed DNA (bacteria and yeasts)
- interspersed DNA that does not seem to carry critical information
- junk DNA
- its usefulness to the cell has not been demonstrated
- proper expression of certain genes
__ can vary widely; because of difference in the __, the genome of similar organisms can vary several hundredfold in their DNA content, even though they contain the same number of genes
It is not a great handicap for __
- Genome size
- amount of excess DNA
- eukaryote to carry a lot of excess DNA
How the genome is __ also differs among eucaryotes, regardless of relationship
There is no relationship between __, __, and __.
The __ and __ have each been shaped by a unique history of seemingly random __, acted on by __ over long evolutionary times
- divided into chromosome
- chromosome number, species complexity, and total genome size
- genome and chromosome
- genetic events
- selection pressures
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