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30 Cards in this Set
- Front
- Back
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What causes hereditary variation within a species?
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allelic variation
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What are alleles?
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different forms of the same gene that differ from one another
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What are the three fundamental properties required of genes and the DNA they are composed of?
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-replication
-generation of form -mutation |
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What is a zygote?
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-a fertilized egg
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What is an organisms genome?
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-the basic complement of DNA (genetic make-up of organism)
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What are cells with two copies of their genome called?
How about only one set? |
-diploid
-haploid |
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Where are genes found?
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-On chromosomes (numbers present may vary)
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What are homologous chromosomes?
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-two chromosomes that contain the same gene array
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What is a gene?
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-a threadlike section of DNA that dictate the inherent properties of a species
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What are the building blocks of DNA?
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-nucleotides
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What are nucleotides composed of?
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-a phosphate group
-molecule of deoxyribose sugar -one of four different nitrogenous bases |
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What are the 4 different nitrogenous bases that make up nucleotides (along with phosphate and deoxyribose sugar)?
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-adenine (goes with T)
-guanine (goes with C) -cytosine (goes with G) -thymine (goes with A) |
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What holds the DNA strands together?
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-weak bonds formed by complementary base pairs in a "lock-and-key" fit
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What does complementary mean (in terms of base pairs)?
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-bases can only pair with a certain other base such as A&T, C&G
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During replication, what joins new nucleotides into the proper strand?
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-DNA polymerase
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If DNA represents information, what constitutes form at the cellular level?
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-proteins
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What are the two basic functions of proteins?
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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) |
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What makes up a protein?
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-a linear chain of polypeptides
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What does a protein look like?
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-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 |
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What determines the final state of a protein (how it folds)?
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-sequence of amino scids specified by its gene
-and the physiology of the cell during folding |
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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)
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What is the difference between base pairing in RNA compared to DNA?
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-Thymine is replaced with Uracil (which pairs with Adenine)
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Once the RNA transcript is made (the strand formed during transcription), what happens?
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-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 |
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What is the definition of translation?
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-the process of making a chain of amino acids based on teh sequence of nucleotides in the mRNA
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How does translation occur?
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-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 |
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During translation, ribosomes read the mRNA in codons...what are codons?
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-groups of three successive bases (AUCG)
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How many ribosomes exist on an mRNA?
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-many of them; they form a train and ALL produce the same protein
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How is a gene composed in terms of exons, termination codons, etc?
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-start with regulation of initiation and transcription
-alternating exon/intron (begin and end with exon) -end with termination of transcription |
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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 |
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What are "housekeeping" genes?
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-protein-encoding genes that are transcribed more less constantly
-always needed for basic reactions |
