Life Science

Chapter 5- Genetics

Key Vocabulary Words:

Probability- chance an event will occur

Trait- characteristic of an organism, such as hair color, eye color, tall or short stems

Express- Show the characteristic

I. Genetics - the study of how traits are inherited.

a.      Mendel- father of genetics, studied plants and determined the pattern of inherited traits and could predict the probability of inheriting traits.

Heredity: passing on traits to next or future generations

1.      A gene or group of genes on chromosome(s) control(s) each trait.

2.      In sexual reproduction, the organism receives genes from each parent for almost every trait (exception- sex linked traits on X and chromosomes)

3.      Alleles- the different forms a gene may have for a trait.

4.      Mendel- noticed that with some traits, even though the organism had two different alleles for a trait, (an example is tall and short stem pea plants, that one allele seems to always express itself over the other.

Tall is expressed over short

5.      The trait that “dominated =dominant trait.

6.      The trait that seemed to disappear was said to be recessive.

7.      Both alleles for a certain trait alike = purebred (homozygous)

8.      If both alleles are different = crossbred or hybrid (heterozygous)

9.      Incomplete dominance: trait is somewhere in between the different alleles; both traits are expressed, example:

10.  Multiple alleles: both traits are expressed (co-dominant); blood type is an example.

11.  Polygenic inheritance: more than one gene ( a group of genes) controls a trait; eye color, skin color

12.  Genotype: genetic makeup of an organism- what genes an organism has for a trait.

13.  Phenotype: the physical appearance of the trait

Predictions and Probability: making a guess about something in the future based on what happened in the past by determining the possibility of something happening.

1.      Punnett Square: a tool for determining the possibility of a trait being handed down and expressed.  Capital letter = dominant allele for trait; lower case letter = recessive allele

 

 

 

 

 

 

 

 

 

II Human Genetics:

A.     Unwanted genetic traits (over 3000 genetic disorders)

  1. caused by an unwanted/harmful mutation
  2. may be passed on to offspring
  3. usually recessive (therefore both alleles must have the trait for it to be expressed- if not they are a carrier for the trait)

B.     Recessive genetic disorders

  1. sickle-cell anemia- red blood cells have a sickle shape/ can’t transport enough oxygen
  2. Cystic fibrosis- thick mucus instead of thin lubricating fluid produced to lubricate lungs etc
  3. Sex-linked disorders: disorders that are linked to the X  sex chromosome (almost all are on the X chromosome). If the male has an X chromosome with the trait he will have the trait. If a female has two X’s each with the trait she will have it. If only one X has the trait she will be a carrier of the trait.

C.     Genetic Engineering: changing DNA sequence of a gene already used to make medicine and improve crops (disease and drought resistant and more yield = nutritious)

 

III. Human Genome Project: All human genetic material

a.      DNA sequencing: determining order and location of each gene

b.      Info can be used to determine risk or possibility of expressing or carrying a genetic disease.

c.       Repair genetic disorders

           

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

II Human Genetics:

D.    Unwanted genetic traits (over 3000 genetic disorders)

  1. caused by an unwanted/harmful mutation
  2. may be passed on to offspring
  3. usually recessive (therefore both alleles must have the trait for it to be expressed- if not they are ar carrier for the trait)

E.     Recessive genetic disorders

  1. sickle-cell anemia- red blood cells have a sickle shape/ can’t transport enough oxygen
  2. cystic fibrosis- thick mucus instead of thin lubricating fluid produced to lubricate lungs etc
  3. Sex-linked disorders: disorders that are  linked to the X  sex chromosome (almost all are on the X chromosome). If the male has an X chromosome with the trait he will have the trait. If a female has two X’s each with the trait she will have it. If only one X has the trait she will be a carrier of the trait.

F.      Genetic Engineering: changing DNA sequence of a gene already used to make medicine and imrove crops (disease and drought resistant and more yield = nutritious)

 

III. Human Genome Project: All human genetic material

d.      DNA sequencing: determining order and location of each gene

e.      Info can be used to determine risk or possibility of expressing or carrying a genetic deisease.

f.        Repair genetic disorders