Chapter 11 Flashcards
Gregor Mendel
The father of genetics
Genetics
The scientific study of heredity
What is the male sex structure on a plant?
The stamen
What is the female sex structure of a plant?
The pistil
Where are the plants’ sperm cells found?
The pollen
Fertilization
When the male and female reproductive cells join in sexual reproduction.
Self pollination
When the sperm cell in the pollen fertilizes the egg cell of the same plant.
True breeding
Self pollinating that results in the offspring being identical to their parent.
How is self pollination prevented?
Cutting away the pollen-bearing male parts called the stamen.
Cross pollinating
Taking pollen grains from one plants and dusting them on another.
What did Mendel’s experiments allow him to do?
Cross breed plants with different characteristics and study the results.
Trait
A specific characteristic that varies from one individual to another.
What traits did Mendel study?
Seed shape, seed color, pod shape, pod color, flower position, flower color, and plant height.
What is significant in how these traits vary with the pea plant species?
They each only had two contrasting characteristics.
What did Mendel call the original pair of plants’ generation?
P (parental)
True or false: Mendel called the first generation of offspring the F1 generation.
True
Hybrids
The offspring that result from a cross between parents with different traits.
Factors (genes)
Determined biological inheritance.
Alleles
Different forms of genes
The Principle of Dominance
Some alleles are more dominant while other are recessive. Recessive can only be seen in the absence of dominant alleles.
How did Mendel get his F2 generation?
By allowing his F1 generation to self pollinate.
Law of Segregation
The alleles segregated from one another during the formation of gametes.
Probability
The likelihood that a particular event will occur.
True of false: past outcomes ALWAYS affect future outcomes.
False
Punnett Square
A diagram used to predict the possible outcomes of genetic crosses.
Homozygous
Organisms that have two identical alleles for a particular trait.
Heterozygous
Organisms that have two different alleles for a particular trait.
Phenotype
Describes the physical characteristics
Genotype
Describes the genetic make up.
What did Mendel get in he F2 generation when he did a two-factor cross?
He found combinations of the two alleles not found in either parent.
Principle of Independent Assortment
Genes for the different traits can segregate independently during the formation of gametes.
Incomplete dominance
Neither allele is dominant over the other. (Red+white=pink)
Codominance
Both alleles contribute to the phenotype. (Black+white=black with white dots)
Multiple alleles
Genes have more than two alleles (blood type)
Polygenic traits
Traits controlled by two or more genes (skin color)
True or false: Mendel’s principles can be applied to all organisms.
True
What else plays a role in determining characteristics?
The environment
Homologous chromosomes
Chromosomes that have a corresponding chromosome from the opposite-sex parent.
Diploid
Cell that contains both sets of homologous chromosomes. (2N)
Haploid
Cell that contains only a single set of chromosomes. (N)
What cells are haploid?
Gametes
Meiosis
The process of reduction division in which the number of chromosomes per cell is cut in half by separating homologous chromosomes in a diploid cell.
What are the 3 main steps in meiosis?
Interphase
Meiosis 1
Meiosis 2
Interphase 1
DNA gets replicated forming duplicate chromosomes.
Prophase 1
Each chromosome pairs with its corresponding homologous chromosome to form a tetrad.
Crossing over
Homologous chromosomes exchange portions of their chromatids, producing new combinations of alleles. (Prophase 1)
Metaphase 1
Spindle fibers attach to chromosomes.
Anaphase 1
Chromosomes are pulled toward opposite ends of the cell.
Telophase 1 and cytokinesis
Nuclear membrane forms and the cell separates into two.
True or false: interphase 2 does not exist
True
Prophase 2
Two diploid daughter cells, each with the same number of chromosomes as the original cell. No chromosomes replicated.
Metaphase 2
Chromosomes align in the center of the cell.
Anaphase 2
Sister chromatids separate and move toward opposite ends of the cell.
Telophase 2 and cytokinesis
4 haploid daughter cells.
Polar bodies
Three gametes produced but not involved in reproduction. (Disintegrate into body)
Thomas Hunt Morgan
Questioned why many traits were inherited together.
Gene linkage
Chromosomes assort independently, not individual genes. Each chromosome is actually a group of linked genes.
Name one reason why a cell divides.
- Information overload; too much DNA.
- Exchange of materials or ratio of surface area: volume gets too small.
