Download Chapter 27: Human Genetics Vocabulary

Chapter 27: Human Genetics
Vocabulary:
Amniocentesis
X­Chromosome
Y­Chromosome
Sex Chromosome
Autosome
incomplete dominance
Sickle­cell Anemia
color blindness
dyslexia
pedigree
I The role of Chromosomes
A The genes that control our traits are found on chromosomes
B Chromosome number
1 Each human sex cell has 23 chromosomes
2 Each human body cell has 46 chromosomes in 23 pairs
3 Different organisms have different chromosome numbers
C Amniocentesis is a way to study the chromosomes of a fetus
D Karyotype is the arrangement of chromosomes for study
1 Males have 22 autosome pairs + XY
2 Females have 22 autosome pairs + XX
E Autosome determine traits other than sex
F Sex chromosomes determine sex: X is the female sex chromosome and Y is the male chreomosome
1 XX will be female, XY will be male
2 Chances of male or female offspring can be predicted by using a Punnett Square
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II Human Traits
A Dominant traits: only 1 gene from either parent is needed for a dominant trait to show up. ex. free earlobes, dimples, curly hair.
B Recessive traits: Two genes, one from each parent is needed for a recessive trait to show up. ex. attached earlobes, no dimples, straight hair.
C Incomplete dominance: A case in which neither gene completely dominates the other.
1 With incomplete dominance a heterozygous individual shows a trait that is a blend between dominant and recessive.
2 An example is the snapdragon plant. Neither red nor white flower genes dominate. The offspring of a red flower plant and white flower plant will be pink
3 Sickle­cell is a condition where the shape of red blood cells are not round but sickle shape
1 The gene for normal cell shape is R and the gene for sickle shape is R'. Neither is dominant.
2 RR is normal, R'R' is sickle­cell anemia, and RR' has both types of cells
3 People with sickle cell anemia (R'R') have serious health problems because their blood cells don't carry enough oxygen.
4 Sickle cell anemia is more common in African Americans than in other races.
5 People with the sickle cell trait RR' usually don't have serious health problems, but may tire easily
D Blood types
1 There are three genes that determine blood type and each person has two of those genes.
2 A gene, B gene, and O gene. The A gene and B gene are dominant to the O gene
3 Blood type genotype
A
AA, AO
B
BB, BO
AB
AB
O
OO
E Genes on the X chromosome
1 X chromosome has more genes than the Y chromosome
2 Color vision is a gene on the X chromosome but not on the Y 3 C normal color vision is dominant to c colorblindness
4 CC normal vision female
Cc normal vision female who carries the gene
cc color­blind female
CY normal vision male
cY color­blind male
5 Males inherit the gene for color vision from their mother only. Females inherit a gene from both their mother and father.
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III Genetic Disorders: Diseases that are inherited
A Errors in Chromosome number
1 Occurs when sperm or egg do not have the proper 23 chromosomes
2 This occurs during meiosis when chromatids fail to split properly
3 examples:
a XXY Klinefelter's syndrome
b XO Turner's syndrome
c Chromosome 21 xxx Down syndrome
B Sex chromosome disorders
1 Hemophilia is a disorder where blood doesn't clot. The is inherited on the X chromosome and affects males more than females
C Autosome disorder (mistake on the autosome)
1 dyslexia
2 PKU
3 Cystic fibrosis
D Genetic counseling ­ use of genetics to predict and explain a child's traits
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