Chapter 9

Questions :

What are Mendel's four hypothesis ?

There are alternative versions of genes that account for variations in inherited chracters.

For each character, an organism inherits two alleles, one from each parent.

If the two alleles of an inherited pair differ, then one determines the organism's appearance and is called the dominant allele,the other has no noticeable effect and is called and is called the recessive allele.

A sperm or egg carries only one allele for each inherited character because allele pairs separate from each other during the production of

gametes.

How technology helps find the chromosomal disorders ?

Due to new technologies we are to get tested for chromosomal disorders. For examples fetal testing, during which the doctor is able to detect harmful genetic conditions of the child, such as Down syndrome etc.... This testing is very helpful because our recessive alleles don't show themselves until we passed them on then they might have chance to affect the genes which could cause some harmful effects.

What is the difference between phenotype and genotype ?

Phenotype is genetic composition that is expre

ssed by organisms. This could be eye color, shape of nose, skin color etc.. On the other hand genotype is the genetic information that is inside the DNA. These are the traits that we're not able to see but we can pass them on and they could show in the next generation.

Diagram :

This diagram shows Punnett square. This square helps to discover the genetic combination if you have two heterozygous plants reproduce.

5facts:

Sex-linked disorders affect mostly males.

One single gene is capable of affecting many phenotype characters.

Environment we are living in may affect many characters.

We have two types of disorders recessive cause by the recessive gene and dominant disorders cause by the dominant gene.

Punnett square shows the possible gene combination based on the Mendel's hypothesizes

Key terms :

Alleles - alternative versions of a gene

Homozygous organism - organism that has two identical alleles

Heterozygous organism - organism that has two different alleles

Phenotype - organism's physical traits

Genotype - organism's genetic traits

Character - heritable feature

Trait - variant for a character

Hybrids - offsprings of two different varieties

Complete dominance - the dominant allele had the same phenotypic effect whether present in one or two copies

Incomplete dominance - some character's phenotype falls between two parental varieties

Video :

Punnett square

Summarize :

Chapter 9 gives a lecture about genetic informations and how are genes inherited. It describes Mendel's hypothesis and Punnett square which shows us the probability of inherited factors.