GeneticsGenetics

Various forms of a gene at a given locus are Various forms of a gene at a given locus are called:called:

AllelesAlleles Mendel chose …… plants as his test Mendel chose …… plants as his test

subject.subject. Pea Pea

If A is dominant to a, the genotypes AA and Aa If A is dominant to a, the genotypes AA and Aa have the same:have the same:

Phenotype.Phenotype. The FThe F22 phenotypic ratio of a monohybrid cross phenotypic ratio of a monohybrid cross

is:is: 3:13:1 The phenotypic ratio of a testcross is:The phenotypic ratio of a testcross is: 1:11:1

The FThe F22 phenotypic ratio of a dihybrid cross phenotypic ratio of a dihybrid cross is :is :

9:3:3:19:3:3:1 B is dominant to b, The cross Bb X bb is B is dominant to b, The cross Bb X bb is

called:called: Testcross.Testcross.

PKUPKU TESTTEST

This disease is known to be caused by an:This disease is known to be caused by an: Autosomal recessive gene.Autosomal recessive gene.

DMD: Duchenne Muscular DystrophyDMD: Duchenne Muscular Dystrophy

How a boy with How a boy with DMD risesDMD rises

DMD is an ………. trait DMD is an ………. trait in humans.in humans.

X-linked recessive.X-linked recessive. What is the What is the genotypegenotype

of a normal man of a normal man whose brother has DMD? whose brother has DMD?

XX (D) (D) YY Can this man be a carrier?Can this man be a carrier? NONO If he marries a normal woman X (D) X (D), If he marries a normal woman X (D) X (D),

what is the probability that their children what is the probability that their children will have DMD?will have DMD?

O%O%

Pedigree of DMD, an X-linked genePedigree of DMD, an X-linked gene

The Royal Hemophilia Pedigree:The Royal Hemophilia Pedigree: Hemophilia is an ……...traitHemophilia is an ……...trait

NicolasNicolas, Czar of Russia (right), married , Czar of Russia (right), married AlexandraAlexandra (left), (left), granddaughter of Victoria of England (1819-1901). granddaughter of Victoria of England (1819-1901). Alexis Alexis

inherited the hemophilia allele and suffered serious bleeding.inherited the hemophilia allele and suffered serious bleeding.

ColorblindnessColorblindness

Colorblindness is an …...trait in humans.Colorblindness is an …...trait in humans. X-linkedX-linked A colorblind woman has the following A colorblind woman has the following

genotype (the gene is designated by D):genotype (the gene is designated by D): XX(d) (d) XX (d) (d) If this woman marries a normal man:If this woman marries a normal man: their ……. will be colorblind, …… will be their ……. will be colorblind, …… will be

carriers.carriers.

Down SyndromeDown Syndrome::Trisomy 21 wasTrisomy 21 was first first described in 1866 by described in 1866 by J. Langdon DownJ. Langdon Down

Syndrome means:Syndrome means: A set of symptoms that occur together.A set of symptoms that occur together. The sex chromosome composition of a person The sex chromosome composition of a person

with with KlinefelterKlinefelter syndrome is: syndrome is: XXYXXY The sex chromosome composition of a person The sex chromosome composition of a person

with with TurnerTurner syndrome is: syndrome is: XOXO

Correlation between maternal age and Correlation between maternal age and the incidence of Down syndromethe incidence of Down syndrome

As women age, As women age, the chances they the chances they will bear a child will bear a child with with Down Down syndromesyndrome increase increase

A chromosome’s gene sequence that was A chromosome’s gene sequence that was ABCDEFGHABCDEFGH before damage and before damage and ABCFG HABCFG H after is an example of: after is an example of:

DeletionDeletion

A chromosome’s gene sequence that was A chromosome’s gene sequence that was ABCDEFGHABCDEFGH before modification and before modification and ABCDLMNOP ABCDLMNOP afterward is an example of:afterward is an example of:

TranslocationTranslocation A chromosome’s gene sequence that was A chromosome’s gene sequence that was

ABCDEFGHABCDEFGH before modification and before modification and ABCDCDCDEFGHABCDCDCDEFGH afterward is an example of: afterward is an example of:

DuplicationDuplication

A chromosome’s gene sequence that was A chromosome’s gene sequence that was ABCDEFGHABCDEFGH before damage and before damage and ABFEDCG HABFEDCG H after is an example of: after is an example of:

InversionInversion

Bacteriophages are:Bacteriophages are: VirusesViruses In DNA, complementary base pairing occurs In DNA, complementary base pairing occurs

between:between: Adenine and thymine, guanine and cytosine A-T Adenine and thymine, guanine and cytosine A-T

pairs and G-C pairspairs and G-C pairs If cytosine makes up 15% of the bases in a DNA If cytosine makes up 15% of the bases in a DNA

molecule. The base A makes up what proportion of molecule. The base A makes up what proportion of the bases?the bases?

35%35% In the pairing of two nucleotides within the In the pairing of two nucleotides within the

double helix:double helix: Hydrogen bonds are used.Hydrogen bonds are used. The base order of one strand of a DNA The base order of one strand of a DNA

molecule is: molecule is: 5’ G A A T T C 3’ 5’ G A A T T C 3’ what is thewhat is the most likely sequence of the other strand?most likely sequence of the other strand?

3’ C T T A A G 5’3’ C T T A A G 5’

If the codon that specifies an amino acid is If the codon that specifies an amino acid is AUA, the base sequence of the anticodon AUA, the base sequence of the anticodon is:is:

UAUUAU Genetic information flows:Genetic information flows: DNADNA RNA Protein RNA Protein Transcription TranslationTranscription Translation

A change in the sequence of DNA bases A change in the sequence of DNA bases (mutation) results in a change in the (mutation) results in a change in the sequence of bases in mRNA, which can sequence of bases in mRNA, which can result in a change in the sequence of amino result in a change in the sequence of amino acids in a polypeptide chain. These changes acids in a polypeptide chain. These changes can destroy the functions of proteins can destroy the functions of proteins (products of genes). (products of genes).