Transcript 12.4 Notes - Trimble County Schools

12.4 NOTES
Important Vocabulary
OBJECTIVES
• Contrast chromosomes and genes
• Learn how the Punnett square is used to
determine the genotype and phenotype of
offspring
VOCABULARY
• Genes- A segment of DNA nucleotides that
code for a specific characteristic
• Chromosomes – long strands of DNA (46 in
humans)
• Egg – female gamete
• (haploid with 23 chromosomes)
• Sperm – male gamete
• (haploid with 23 chromosomes)
MORE VOCABULARY
• Zygote – fertilized egg
• (diploid with 46 chromosomes)
• X and Y chromosomes determine sex
• XX – female
XY – male
• Locus – the position of a gene on a chromosome
• Alleles – different forms of a gene
• Homozygous – gene pair that is the same (AA or aa)
• Heterozygous – gene pair that have different alleles (Aa)
EVEN MORE VOCABULARY
• Dominant – traits that mask the recessive
(in blood that is A and B)
• Recessive – traits that only appear when
paired with another allele that is
recessive (type O)
• Genotype – a pair of allele genes
• Phenotype – the outward appearance of
an individual
BLOOD TYPES
• Individual inherits two similar genes from
parents
• Type A = AA, AO (or Ai)
• Type AB = AB
• Type B = BB, BO (or Bi)
• Type O = OO (or ii)
• Type = phenotype
• Genotype determined by family history
PUNNET SQUARE
• No blood group
gene can appear
in a child unless
it is present in at
least one of the
parents
PATERNITY TESTING
• Normally encountered in civil courts
• Relate suspected parents and offspring to their
blood group systems
• Involves A-B-O
• HLA (human leukocyte antigen) found on white
blood cells
• If suspect cannot be excluded, the chances are
better than 90% that he is the father
• DNA – raise odds to beyond 99%
12.4 QUESTIONS
1. Differentiate between gene and chromosome.
2. Differentiate between heterozygous and
homozygous gene pairs.
3. Differentiate between genotype and phenotype.
4. Draw 3 Punnet Squares based on the following
information:
A. Parent 1 (AO), Parent 2 (BO)
B. Parent 1 (AA), Parent 2 (AB)
C. Parent 1 (OO), Parent 2 (AO)