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30 Cards in this Set

  • Front
  • Back
What causes hereditary variation within a species?
allelic variation
What are alleles?
different forms of the same gene that differ from one another
What are the three fundamental properties required of genes and the DNA they are composed of?
-generation of form
What is a zygote?
-a fertilized egg
What is an organisms genome?
-the basic complement of DNA (genetic make-up of organism)
What are cells with two copies of their genome called?
How about only one set?
Where are genes found?
-On chromosomes (numbers present may vary)
What are homologous chromosomes?
-two chromosomes that contain the same gene array
What is a gene?
-a threadlike section of DNA that dictate the inherent properties of a species
What are the building blocks of DNA?
What are nucleotides composed of?
-a phosphate group
-molecule of deoxyribose sugar
-one of four different nitrogenous bases
What are the 4 different nitrogenous bases that make up nucleotides (along with phosphate and deoxyribose sugar)?
-adenine (goes with T)
-guanine (goes with C)
-cytosine (goes with G)
-thymine (goes with A)
What holds the DNA strands together?
-weak bonds formed by complementary base pairs in a "lock-and-key" fit
What does complementary mean (in terms of base pairs)?
-bases can only pair with a certain other base such as A&T, C&G
During replication, what joins new nucleotides into the proper strand?
-DNA polymerase
If DNA represents information, what constitutes form at the cellular level?
What are the two basic functions of proteins?
1) structural component (for physical properties of cells and organisms) OR
2) it may be an active agent in cellular processes (such as an active-transport protein or an enzyme)
What makes up a protein?
-a linear chain of polypeptides
What does a protein look like?
-coiled and folded chain that complements the sequence of nucleotides in the gene
-sometimes associated with other chains or small molecules to form a functional protein
What determines the final state of a protein (how it folds)?
-sequence of amino scids specified by its gene
-and the physiology of the cell during folding
What is the first step in making a protein?
What is the definition of this?
-transcription (copying the nucleotide sequence in one strand of the gene into a complementary single-stranded molecule of RNA)
What is the difference between base pairing in RNA compared to DNA?
-Thymine is replaced with Uracil (which pairs with Adenine)
Once the RNA transcript is made (the strand formed during transcription), what happens?
-it may undergo some structural modicications and becomes the "working copy" of the gene information (mRNA)
-mRNA enters cytoplasm and is used by the cellular machinery to direct protein manufacture
What is the definition of translation?
-the process of making a chain of amino acids based on teh sequence of nucleotides in the mRNA
How does translation occur?
-ribosome attaches to one end of mRNA molecule and catalyzes assembly of amino acid string (consitutes primary polypeptide chain of the protein)
-tRNA brings the complementary AA for ribosome to attach
-ribosome detaches when it reads a termination codon (such as UAG).
*Ribosome can then recycle and be used on another mRNA
During translation, ribosomes read the mRNA in codons...what are codons?
-groups of three successive bases (AUCG)
How many ribosomes exist on an mRNA?
-many of them; they form a train and ALL produce the same protein
How is a gene composed in terms of exons, termination codons, etc?
-start with regulation of initiation and transcription
-alternating exon/intron (begin and end with exon)
-end with termination of transcription
Are introns found in all cells?
What function do they have?
-No, prokaryotes don't have introns
-unknown; they are excised when primary transcription occurs so mRNA does not have them
What are "housekeeping" genes?
-protein-encoding genes that are transcribed more less constantly
-always needed for basic reactions