Heredity and Genetics Notes

Offspring—individuals created by parents

            --offspring get some traits from mother/ some from father

            --traits cannot “skip a generation”

          —they just may not be expressed (seen)        every time 

Heredity—passing of traits and characteristics from parents to offspring

            Trait—genetically determined characteristic

 

Genetics—study of how traits are passed from parents to offspring

            --genetics has become a huge field of study (implications in medicine, agriculture, etc)

 

What causes traits?

Chromosomes—structures that contain information for all traits you have

       --located in the nucleus of every cell

       --humans have 23 pairs of chromosomes

           (or 46 individual chromosomes)

 

 

 

Genes—tiny sections of chromosomes that contain codes for certain traits

 --a single chromosome can contain thousands of genes

 --more than 90,000 genes in the human body

Deoxyribonucleic Acid (DNA)—basic unit of genetic material

 --makes up genes

 --shaped is a double helix (like a twisted ladder)

 --made of 4 different substances called “bases”

4 Bases:

Adenine, Thymine, Cytosine, Guanine

  • Adenine and Thymine pair off;
  • Cytosine and Guanine pair off

 genes of all living things are made of these 4 bases

Copying/ making new DNA strands:

 

--biggest difference between organisms is the order (sequence) the bases are combined in to form genes (and the number of chromosomes containing genes)      

 

--All living things share certain DNA sequences

            --organisms with more sequences in common are more closely related

                        (humans are more closely related to other mammals than to reptiles, etc)

            --humans have over 70 trillion possible combinations

**DNA is the blueprint, the set of instructions, to make all organisms**