Honors Biology Chapter 10: The Structure and Function of DNA (Semester 2)
Terms in this set (65)
-Was known to be a chemical in cells by the end of the nineteenth century
-Has the capacity to store genetic information
-Can be copied and passed down from generation to generation
The study of heredity at the molecular level
DNA and RNA are...
They (DNA and RNA) consist of chemical units called ____.
A nucleotide polymer is a _____.
Where are nucleotides joined?
Covalent bonds between the sugar of one nucleotide and the phosphate of the next, forming a sugar-phosphate backbone
What is the sugar in DNA?
What is the full name of DNA?
The four nucleotides found in DNA differ in their...
What are the four nucleotide bases?
RNA has ____ in place of thymine.
What is the sugar in RNA (which in place of deoxyribose)?
James Watson and Francis Crick determined that DNA is a _____.
What did Watson and Crick use to reveal the basic shape of DNA?
What did Rosalind Franklin do?
She produced the x-ray image of DNA
What must happen when a cell reproduces?
A complete copy of the DNA must pass from one generation to the next
What did Watson and Crick's model of DNA suggest?
It suggested that DNA replicates by a template mechanism
What can DNA be damaged by?
X-rays and ultraviolet light
DNA polymerases info
-make the covalent bonds between the nucleotides of a new DNA strand
-are involved in repairing damaged DNA
What does DNA replication ensure?
It ensures that all the body cells in multicellular organisms carry the same genetic information
DNA replication in eukaryotes
-begins at specific sites on a double helix (called origins of replication) and
-proceeds in both directions
What does DNA generally do?
DNA provides instructions to a cell and an organism as a whole
A organism's _____ is its genetic makeup, the sequence of nucleotides bases in DNA.
The _____ is the organism's physical traits, which arise from the actions of a wide variety of proteins.
DNA specifies the synthesis of proteins in what two stages?
transcription and translation
The transfer of genetic information from DNA into an RNA molecule
The transfer of information from RNA into a protein
What is the flow of information from gene to protein based on?
A triplet code
What is a codon?
It is a triplet of bases, which codes for one amino acid
What is the genetic code?
It is the set of rules that convert a nucleotide sequence in RNA to an amino acid sequence
Of the 64 triplets,
-61 code for amino acids
-3 are stop codons, instructing the ribosomes to end the polypeptide
-There are 20 amino acids common to all living things
-DNA is a template to make RNA (mRNA)
-Resembles the synthesis of a DNA strand during DNA replication, but substitutes uracil (U) for thymine (T)
RNA polymerase definition
The transcription enzyme that links RNA nucleotides
RNA processing includes
-Adding a cap and tail consisting of extra nucleotides at the ends of the RNA transcript
-Removing introns (noncoding regions of the RNA)
What does RNA processing do?
It protects the RNA from attack by cellular enzymes and helps ribosomes recognize the RNA as mRNA
Apart of RNA proccesing is RNA splicing, joining ___ (the parts of the gene that are expressed) together to form _____ (mRNA)
exons, messenger RNA
What is RNA splicing believed to do?
Play a significant role in humans
How does RNA splicing play a significant role in humans?
-In allowing our approximately 21,000 genes to produce many thousands more polypeptides
-By varying the exons that are included in the final mRNA
What does translation do?
It converts the nucleic acid (DNA) into the protein language
-transfer RNA (tRNA)
Ribosomes are organelles that:
-coordinate the functions of mRNA and tRNA
-are made of two subunits
Each subunit is made up of:
-a considerable amount of another kind of RNA, ribosomal RNA (rRNA)
Transfer RNA (tRNA):
-acts as a molecular interpreter
-carries amino acids
-matches amino acids with codons in mRNA using anticodons, a special triplet of bases that is complementary to a codon triplet on mRNA
In a cell genetic information flows from:
-DNA to RNA in the nucleus (transcription)
-RNA to protein in the cytoplasm (translation)
As it is made, a polypeptide (protein)
coils and folds and assumes a three-dimensional shape, its tertiary structure
____ and _____ are how genes control the structure and activity of cells
-A mutation is any change in the nucleotide sequence of DNA
-Mutations can change the amino acids in a protein
Mutations can involve:
-Large regions of a chromosome
-Just a single nucleotide pair, as occurs in sickle-cell disease
Mutations within a gene can be divided into two general categories:
1. Nucleotide substitution (the replacement of one base by another)
2. Nucleotide deletions or insertions (the loss or addition of a nucleotide)
-Have no effect (same amino acid)
-Change on amino acid
Insertions and deletions can:
-Change the reading frame of the genetic message
-Lead to disastrous effects
Mutations may result from:
-errors in DNA replication or recombination
-Mutagens-physical or chemical agents
Mutations (not definition):
-are useful in nature and the laboratory as a source of genetic diversity, which makes evolution by natural selection possible
Viruses share some, but not all, characteristics of living organisms. Viruses:
-posses genetic material in the form of nucleic acids wrapped in a protein coat
-are not cellular
-cannot reproduce on their own
What are bacteriophages or phages for short?
They are viruses that attack bacteria
What do phages consist of?
A molecule of DNA, enclosed within an elaborate structure made of proteins
What are the two reproductive cycles of phages?
In the lytic cycle:
-Many copies of the phage are produced within the bacterial cell
-then the bacterium lyses (breaks open)
In the lysogenic cycle:
-The phage DNA inserts into the bacterial chromosome
-the bacteria reproduces normally, copying the phage at each cell division
Viruses that infect plant can
-Diminish plant yields
What do most known plant viruses have as their genetic material?
What are many plant viruses like?
They are rod-shaped with a spiral arrangement of proteins surrounding the nucleic acid (tobacco mosaic virus are like this)
Since viral plant diseases have no cure, how are they prevented?
They are best prevented by producing plants that resist viral infection
Viruses that infect animals:
-are a common cause of disease
-may have RNA or DNA genomes
What are many animal viruses like?
Many animal viruses have an outer envelope made of phospholipid membrane, while projecting spikes of protein
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