Chapter 14 Flashcards

Question

What is complete dominance? (3)

Answer 1

phenotype of the heterozygote and the dominant homozygote are indistinguishable When the dominant allele overpowers the recessive allele Example- Mendel’s peas, with purple flowers showing complete dominance

Answer 2

-when hybrids have a phenotype somewhere between those of two parental varieties Example- when a red and white snapdragon crosses to produce pink snapdragons Results when heterozygote offspring has less red pigment than the homozygous parent

Answer 3

wo alleles each affect the phenotype in separate, distinguishable ways

Answer 4

MN blood groups Homozygous M allele have red blood cells with only M molecules Homozygous N alleles have red blood cells with only N molecules Heterozygous MN groups have both M and N alleles and result with distinguishable effects from both groups

Answer 5

When dominant alleles and recessive alleles coexist in a heterozygote, they do not interact During the path from genotype to phenotype, dominance, and recessiveness comes into play

Answer 6

Mendel’s round (dominant) vs wrinkled (recessive) pea seed shape The dominant allele has the code for an enzyme that converts unbranched forms of starch to branched from in the seed Recessive allele codes for a defective form of the said enzyme, leading to an accumulation of unbranched starch Excessive water enters the seed through osmosis. As the seed dries, it wrinkles Dominant allele present prevents excess water from entering the seed and prevents wrinkling when drying

Answer 7

For any character, the observed dominant/ recessive relationship of alleles depends on the level at which we examine the phenotype

Answer 8

Tay Sachs disease (cannot metabolize certain lipids because of defective enzymes, causing excess lipids) Results when a child inherits two copies of the Tay Sachs allele (homozygotes) Organismal level- recessive Biochemical level- incomplete dominance Heterozygote lipid metabolization is between homozygous of normal alleles and homozygous of tay-sachs disease Heterozygotes have enough lipid metabolization to prevent disease Molecular level- codominant Heterozygous individuals produce equal numbers of normal and defective enzymes

Answer 9

Dominant alleles are not always more common Example polydactyly (extra finger/ toe) For those with polydactyly, the presence of a dominant allele results with said disorder

Answer 10

Although Mendel’s pea character’s genes had only two alleles, most genes have more Example- ABO blood groups Determined by three alleles: IA (type A), IB (type B), i (none) Results with one of four types, A, B, AB, or O A and B are carbohydrates found on the surface of red blood cells O have neither

Answer 11

Genes having multiple phenotypic effects Associated with multiple symptoms of certain hereditary diseases like cystic fibrosis and sickle-cell disease In garden peas, gene determining flower color also affects the color of the seed coat

Answer 12

Phenotypic expression of a gene at one locus alters that of a gene at a second locus

Answer 13

labrador retrievers Black coat is dominant to brown coat (Bb) Genotype must be bb for a brown coat Second gene determines whether pigment will be deposited in the hair (Ee) If second gene is homozygous recessive (ee), coat is yellow, no matter the genotype of black/ brown locus

Answer 14

Mendel studied characters as either or Either purple or white flowers Many characters are not discrete Skin color or height

Answer 15

characters that vary in the population in gradations along a continuum Indicates polygenic inheritance Additive effect of two or more genes on a single phenotypic character

Answer 16

Skin pigmentation- consists of three units of alleles- A, B, or C AABBCC is very dark aabbcc is very light AaBbCc is median Same shade as aaBBCc

Answer 17

The environment can affect phenotype Example- tree having various leaf size, shape, greenness, depending on exposure to wind and sun Example- humans having various height (nutrition), build (exercise), and skin shade (sun tanning) Genotype is not associated with a rigidly defined phenotype Blood count is affected by factors like altitude, physical activity, and infectious agents

Answer 18

many factors influencing phenotype

Answer 19

a family’s history for a particular trait Collecting information on said trait by looking through the family tree

Answer 20

carry recessive alleles responsible for a disorder Heterozygotes that do not exhibit the disorder but carry the recessive allele

Answer 21

Inbreeding raises chances of passing recessive alleles because they share common ancestors that are more likely to carry the same recessive allele

Answer 22

Most common lethal genetic disease in the US More common in European descendants Defective chloride transport chains in the plasma membrane Results in a high concentration of chloride in the extracellular matrix Causes mucus buildup in the organs

Answer 23

Two recessive sickle cell alleles are necessary for full-blown disease The presence of one allele can affect phenotype Organismal level- incomplete dominant Molecular level- codominant

Answer 24

Achondroplasia- dwarfism 99.9% of the population are homozygous for the recessive allele Huntington’s disease- a degenerative disease of the nervous system A dominant lethal allele that shows no phenotypic effect until 35-45 years

Answer 25

Genetic component plus the significant environmental influence Example-heart disease, diabetes, cancer, alcoholism, schizophrenia, bipolar disorder

Answer 26

technique to determine whether a fetus has tay sachs disease Done in the 14th -16th week Doctor inserts a needle in the uterus and extracts amniotic fluid

Answer 27

doctor inserts a narrow tube through the cervix into the uterus and suctions a sample of tissue from the placenta

Answer 28

examines fetus for major anatomical abnormalities Ultrasound- sound waves used to produce an image Fetoscopy- needle-thin tube containing a viewing scope is inserted in the uterus

Answer 29

phenylketonuria- a recessively inherited disorder Cannot metabolize amino acid phenylalanine This acid and phenylpyruvate accumulate in the blood and causes mental retardation If detected early, a special diet low in phenylalanine will allow normal development

Chapter 14 Flashcards

(53 cards)