What is genetics? (1) Flashcards
What is genetics?
Genetics is a branch of biology that studies heredity and variation in organisms. It tries to explain both the similarities and the differences between parents and their offspring. Parents always produce offspring that look like them in some ways but differ in other ways.
Define heriditary.
Passing on of traits / characteristics from one generation to the next
Who is the father of genetics?
Gregor Mendel (1822–1884), an Austrian monk, lived at about the same time as Charles Darwin, but the two men never met. Mendel often called the ‘Father of Genetics’, was responsible for the first major breakthrough in the study of heredity by investigating the transfer of characteristics from one generation to the next.
What did Mendel realize?
He realized that ‘something is passed on from parent to offspring and that sexual reproduction combines these’ somethings’ from each parent to produce offspring which are unique, yet the same.
In ___ he published his work but it was not recognized in scientific circles until 1900, years after his death.
1866
As ____ theory of evolution was gradually accepted so were Mendel’s findings and laws.
Darwin’s
Many other biologists used Mendel’s research as a basis for their own studies and _____ genetics is studied and taught throughout the world. Gregor Mendel died in Brunn on January 6, 1884.
Mendelian
What are the ‘somethings’ that Mendel first spoke of?
We now know that the ‘somethings’ which are passed from parent to offspring are genes (although Mendel called them ‘factors’), which are part of DNA molecules in chromosomes.
In recent years spectacular advances have been made in understanding the ___ and ___ of these genes.
structure
functioning
What is each chromatid made up of?
Each chromatid is made up of one, helical DNA molecule.
What is each DNA molecule made up of?
Each DNA molecule is made up of a series of genes.
What is a gene?
A gene can be defined as a section of DNA (series of nucleotides/bases) that controls a hereditary characteristic (trait), i.e. it is the basic unit of heredity in living organisms.
Each chromosome has between several hundred and several thousand genes. The total number of genes in humans is thought to be between ___ and _____. It was previously thought to be between 30 000 and 40 000 or even higher.
20 000 and 25 000
What do all somatic cells and mature red blood cells have?
Nearly all somatic cells have an exact copy of all the genes in that organism. Mature red blood cells have no nuclei, therefore no chromosomes and no genes.
Why do nearly all somatic cells have an exact copy of all the genes in that organism?
Because there are two of each kind of chromosome (paternal and maternal), each cell contains two of each kind of gene (before replication). These versions of a gene are known as alleles.
