Chapter 10 Flashcards
Patterns of Inheritance
How can genetics explain and predict inheritance patterns?
-a gene is a segment of DNA that carries the instructions for synthesizing a protein
-genetics can explain why these children look different
-analyzing their genes can also help predict the appearance of their offspring
How can genetics determine body functions and health?
-most genetics encode proteins that have nothing to do with outward appearance
-the enzymes essential to our loves are also the product of genetics
-studying genetics also allows scientists to breed superior crops and doctors to track genetic illnesses
What are chromosomes?
-they are packets of genetic information
-recall that a chromosome is a piece of DNA containing many different genes
-when 2 haploid cells fuse during fertilization, a diploid zygote with two full sets of chromosomes is formed
Define locus
-a genes physical location on a chromosome
Chromosomes are paired into…?
-diploid cells
-each chromosome is a member of a homologous pair
-humans have 22 homologous pairs of autosomes and one pair of sex chromosomes
How many alleles do diploid cells have per gene?
-they have 2 alleles per gene
-members of a homologous pair have the same genes but might have different versions (alleles) of those genes
Are sex chromosomes homologous?
-female sex chromosomes are homologous (XX)
-male sex chromosomes are not homologous (XY)
Gregor Mendel uncovered basic laws of inheritance
-gregor mendel used pea plants to study heredity
-hand pollinating the plants allowed mendel to control plant breeding experiments
1.) pollen from tall plant is transferred to flower on short plant
2.) pods contain the offspring (seeds) resulting from the cross
3.) seeds are planted
4.) each seed develops into a short or tall plant
Define homozygous
-they are true breeding because all of the gametes contain the same allele
-has 2 identical alleles for a particular gene (YY or yy)
Define heterozygous
-they are not true breeding because they pass on either a dominant or recessive allele (hybrid)
-produces a mix of offspring for one or more traits
-has 2 different alleles for a particular gene Yy)
Define wild type
-the most common allele, genotype or phenotype in a population
Define mutant
-an allele, genotype, or phenotype that is not most common in a population or has been altered from the typical (wild type) condition
-when a gene has undergone a mutation
What is the order of the generations P, F1, and F2?
1.) P generation (parental) is the first generation (true breeding)
2.) F1 generation if the offspring of P generation
3.) F2 generation is the offspring of F1 generation in a genetic cross
Define true breeding
-self fertilization yields offspring with the same seed color (homozygous) as parent plant
-true breeding plants produce offspring identical to themselves (in one or more traits)
Define hybrid
-self fertilization yields a mix of seed colors
-hybrid plants outwardly resemble true breeders but produce mixed offspring
Define dominant allele
-dominant alleles express their effects wherever they are present
-crossing a yellow seed plant with a green seed plant will always yield some yellow seeds (yellow seed color is therefore dominant)
-active allele and produces yellow color by encoding a pigment metabolizing enzyme
Define recessive allele
-a recessive allele, like green seed color, is whose effect is masked if dominant allele is also present
-recessive alleles usually encode nonfunctional proteins
-inactive allele
-in the absence of pigment metabolizing enzymes, the seed color stays green
Why do some plants produce both yellow and green seeds?
-the answer has to do with each plant having 2 alleles for each gene
-because of their homologous pair of chromosomes
Define genotype
-it represents an individuals 2 alleles for one gene
-the genotype confers the phenotype (the physical appearance)
Define phenotype
-the physical appearance of the offspring
-look at the offspring to determine the genotype of the parent
-individuals with the same phenotype can have different genotypes
What does a Punnett square do?
-it represents gamete formation and fertilization
-a punnett square uses the genotypes of the parents to reveal which alleles the offspring may inherit
Define a monohybrid cross
-a female parent heterozygous for seed color is crossed with a male parent who is also heterozygous for seed color
-this is a monohybrid cross because both parents are heterozygous
