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PCAT Biology Genetics

Subjects : pcat, biology
  • Answer 50 questions in 15 minutes.
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This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.
1. Fruit fly -produces often (short life cycle) -reproduces in large numbers (large sample size) -chromosomes (especially in the salivary gland) are large and easily recognizable in size and shape -its chromosomes are few (4 pairs - 2n=8) -Mutations occ

2. Diagnostic tool to determine the genotype of an organism -Only with a recessive phenotype can genotype be predicted with 100% accuracy -if dominant phenotype is expressed - the genotype can be either homozygous dominant or heterozygous -used to deter

3. Recessive genes that are carried on the X chromosome will produce the recessive phenotypes whenever they occur in men because no dominant allele is present to mask them -ex: hemophilia and color blindness

4. Double stranded DNA molecule unwinds and separates into two single strands

5. Silent allele -usually assigned capital letters

6. Ribonucleic acid -polynucleotide structurally similar to DNA except that its sugar is ribose -contains uracil instead of thymine -usually single stranded -found in both nucleus and cytoplasm -several types are involved with mRNA - tRNA - and rRNA

7. Virus that infcts its host bacterium by attaching to it - boring a hole through the bacterial cell wall - and injecting its DNA while its protein coat remains attached to the cell wall and enters the host in either a lytic cycle or a lysogenic cycle

8. New codon may code for the same amino acid

9. Occurs when fragments of the bacterial chromosome accidentally become packaged into viral progeny produced during a viral infection

10. Daughter strand that is continuously synthesized by DNA polymerase in the 5'->3' direction

11. Structure formed when many ribosomes simultaneously translate a single mRNA molecule

12. May occur spontaneously or be induced by environmental factors

13. Composed of two subunits (consisting of proteins and rRNA) - one large and one small - that bind together only during protein synthesis -have 3 binding sites (for mRNA and two tRNA)

14. Brings amino acids to the ribosomes in the correct sequence for polypeptide synthesis -recognizes both the amino acid and the mRNA codon

15. Codes for the synthesis of a repressor molecule that binds to the operator and blocks RNA polymerase form transcribing the structural genes

16. The sequence of nontranscribable DNA that is the repressor binding site

17. Occurs when linked genes are separated

18. Begins at a unique origin of and proceeds in both directions simultaneously

19. If the bacterioophage does not lyse its host cell - it becomes integrated into the bacterial genome in a harmless form - lying dorant for one or more generations. the virus mays tay integrated indefinitely - replicating along with the bacterial gneom

20. The process whereby information coded in the base sequence of DNA is transcribed into a strand of mRNA that leaves the nucleus through nuclear pores. the remaining events of protein synthesis occur in the cytoplasm

21. Transfer of genetic material between two bacteria that re temporarily joined

22. Alternative forms of genes when it exists in more than one form

23. The process by which a foreign plasmid is incorporated into the bacterial chromosome via recombination - creating new inheritable genetic combinations

24. Base sequence of mRNA is translated as a series of triplets

25. Consists of a single circular chromosome located in the nucleoid region of the cell

26. Organisms that contain two copies of the same allele

27. Either the failure of homologous chromosomes to separate properly during meiosis I or the failure of sister chromatids to separate properly during meiosis II -zygote might either have 3 copies of that chromosome (trisomy) or just a single copy (monos

28. (AUG) ribosome scans the mRNA until it bonds to this (methionine) and UAC on anticodon of tRNA

29. Genes on the same chromosome will stay together unless crossing over occurs -crossing over exchanges information between chromosomes and may break the linkage of certain patterns

30. Each new daughter helix contains an intact strand from the parent helix and a newly synthesized strand

31. Organisms that carry two different alleles

32. Initiation - elongation - and termination

33. Individuals being crossed

34. Small RNA found in the ctyoplasm that aids in the translation of mRNA's nucleotide code into a sequence of amino acids -brings amino acids to the ribosomes during protein synthesis

35. The noncoding sequence of DNA that serves as the initial binding site for RNA polymerase

36. Genes that are located on the X or Y chromosome -in humans - most are located on the X

37. Can be altered under certain conditions - altering the corresponding characteristics in the organism

38. The ribosome advances three nucleotides along the mRNA in the 5' to 3' direction and the uncharged tRNA from the P site is expelled - and the peptidyl-tRNA from the A site moves into the P site and completes the cycle

39. New codon may code for a different amino acid

40. Nucleic acid is replaced by another nucleic acid

41. Complex that can't bind to the operator - thus permitting transcription

42. Progeny phenotypes are apparently blends of the parental phenotypes

43. Chromosome fragment

44. Bacteriophages that replicate by the lytic cycle - killing their host cells

45. Occurs while multiple alleles exist for a given gene and more than one of them is dominant -expression of both dominant alleles are simultaneous -ex: ABO blood group

46. Phage DNA takes control of the bacterium's genetic machinery and manufactures numerous progeny - causing the cell to lyse - releasing new virions - each capable of infecting other bacteria -if initial infection takes place on a bacterial lawn - then

47. Structural component of ribsomes and is the most abundant of all RNA types -synthesized in the nucleolus

48. (UAA - UAG - or UGA) terminates polypeptide synthesis

49. Binds to the incoming aminoacyl-tRNA complex (Arriving site)

50. Induce mutations -include cosmic rays - X rays - UV rays - and radioactivity