It's All In The DNA
Genetics is the study of heredity or the patterns of inheritance of specific traits, relating to genes and genetic information.
Heredity is the passing of genetic information (DNA) from parent to offspring during sexual reproduction. Each sex cell (egg or sperm) of the parent organism (plant or animal) contains one-half of the genetic information or chromosomes needed to create a new organism.
Chromosomes are structures found in the nucleus of a cell. Chromosomes contain strands of genetic information or DNA. DNA stands for deoxyribonucleic acid. DNA strands are coiled to form a double helix or spiral ladder shape. Segments of a DNA strand code for specific traits. These segments are called genes. Genes typically come in pairs. One gene from the pair is called an allele.
General Resources for Genetic Standards
Tongue Tasting Trivia
2. In general, girls have more tastebuds than boys.
3. Taste is the weakest of the five senses.
4. Insects have the most highly developed sense of taste.
5. Some insects have taste organs on their feet, antennae, and mouth.
5. Fish can taste with their fins, tail, and mouth.
Human Chromosome Chart
The 23rd pair, the sex chromosomes, differ between males and females. Females have two copies of the X chromosome, while males have one X and one Y chromosome. Therefore, males determine the sex of the next generation. Can you calculate the probability for the sex of four children born to the same Dad and Mom?
Mendel Researched Heredity Using Pea Plants
- Mendel planted seeds from purebred "parent" plants.
- He observed how some traits where visible generation to generation.
- He observed how some traits were not visible generation to generation.
- Mendel kept very accurate records for hundreds of individual plants.
- He used statistical analysis (MATH) to study the traits of different generations.
- Through his findings, he proposed that the traits were passed by parents.
- He said the traits that were visible generation to generation were dominant.
- He said the traits that were less visible or rarely visible were recessive.
dominant - a trait that is expressed if present
recessive - a trait is that is expressed if there is not a dominant trait
Traits That Mendel Observed Generation to Generation
trait = seed color
variation = the seed color is either yellow or green
Why Pea Plants?
- easy to grow
- grow quickly
- can be cross pollinated
- few traits
- two variations for traits
Mendel Conducted Monohybrid Experiments.
- one trait at a time was followed
- data was recorded on the variations generation to generation
- a total of seven traits were followed and recorded
- the data showed that some trait variations were more likely to show up
- some trait variations were hidden
The Data Results
- He called the trait variations that showed up dominant
- He called the trait variations that were hidden recessive
- He proposed that traits were controlled by two alleles
- One allele came from the father and one came from the mother
- The trait variation were passed down randomly as alleles
Mendel's Research Results Showed The Following:
How Geneticists Say It
A genotype can be homozygous or heterozygous.
Phenotype is the expression or what we "see" due to genotype combinations.
Labs: Extracting DNA
- traits are simultaneously blended together resulting in a new phenotype
- RW = a pink carnation is expressed or a new phenotype occurs
- both traits are independently expressed within one organism
- Crossing Alleles for Blood Type Traits
1. Check out the Punnett Square below.
2. How's it different from the punnet squares we have been constructing?
3. Can you explain why it is different?
- one characteristic is controlled by two or more genes
- the genes can be large in quantity (# or amount) but small in quality (effect or result)
- human polygenic inheritance include height, skin color, eye color and weight.
- polygenes offer a greater variety of trait expression for a characteristic
- chart below is an example of polygenic inheritance for human height
- a gene located on chromosome #23; X (female) or Y (male)
- the sex chromosome #23 carries one allele from each gene
- it is a gamete cell, or haploid, that is able to fuse with another cell to form life
- gamete is a Greek term which means to marry
Below is a very short list of sex-linked diseases. There are many many more.
Why do you think there are lots of diseases that originate in the DNA of chromosomes?
- Color Blindness
- Sickle Cell Anemia
- Muscular Dystrophy
- Cystic Fibrosis
The pedigree chart below outlines how a sex-linked disease might be passed through generations. Study the key and then the chart, carefully.
When shapes are connected by a line = they reproduce a new generation
1. Use bullet points to explain the information that the chart demonstrates.
Construct scientific arguments using evidence to support claims for how changes in genes (mutations) may have beneficial, harmful, or neutral effects on organisms.
2. A mutation is a relatively permanent change in hereditary material.
3. Mutations are grouped into three types:
- Single Gene Disorder - defect in one gene
- Chromosome Disorder - number or structure of chromosome is changed
- Multifactorial Disorder - multiple genes impacted by environment or lifestyle
4. Mutations orginate in two ways:
- Gamate (germ) cell mutations are passed by sexual reproduction.
- Body (somatic) cell mutations occur randomly in an organisms.
Queen Victoria Hemophilia Pedigree
Technology & Genetics
With the advancement of technology scientists are able to explore the genetic make up of organisms through various types of research. This exploration has led to different methods of research and medical treatments. Some methods of research are controversial.
- broad area of scientific investigations of biological processes and causes for disease
- some investigations are controversial
- investigations can include but are not limited to:
selective breeding - ancient practice of controlling reproduction externally
human genome project - international project which mapped human DNA
cloning - producing identical populations by extracting one parent's DNA to reproduce
stem cell research - using embryonic cells or adult stem cells to create specific cell types
genetic engineering -manipulating the DNA of an organism with own or another's DNA
gene therapy - genes are introduced into the body to treat disease
to selectively develop particular phenotype traits (characteristics)
by choosing which will reproduce and have offspring.
2.Genes are introduced into the body to treat diseases.
3.A healthy gene is introduced to the body with the hope of supplanting the diseased gene.
-the manipulation of DNA in order to produce new types of organisms;
-usually by inserting or deleting genes;
1982 - 1st transgenic animal (mice)
1990 - 1st transgenic plant (maize, wheat)
1993 - regulations put on genetically engineered organisms, or gmo
1994 - gmo tomato sold in USA
2004 - 8.25 million farmers in 17 countries were growing gmo crops