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GENETICS!!!. Genetics. Genetics is the study of the transmission of biological information from one generation to the next. Father of genetics is Mendel. 1. Genes are sections of DNA which are responsible for making a particular protein (a polypeptide).
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Genetics Genetics is the study of the transmission of biological information from one generation to the next. Father of genetics is Mendel
1. Genes are sections of DNA which are responsible for making a particular protein (a polypeptide).
2. Genes are located on chromosomes. Each chromosome has thousands of genes on it.
3. Your genes determine your physical (an mental) characteristics.
4. Humans have 23 pairs of chromosomes. __ total. • 5. You get one set from your mother and one from your father.
6. Each of the pairs consists of 2 homologous chromosomes. These are similar in shape, size, and genetic make-up.
7. This arrangement gives you 2 genes for a characteristic on each chromosome.
8. Alleles are alternate forms of the same gene. Usually one allele will be dominant while one will be recessive.
9. The dominant allele is represented by a capital letter. The recessive by a lower case letter. • 10. A dominant allele will mask a recessive allele.
11. The kinds of genes you have make up your genotype. You cannot see a person genotype because the recessive allele may be masked.
12. The phenotype is the outward expression of your genetic make-up. It can be seen.
13. Each gamete unites at fertilization to form a zygote. • The male gamete is the sperm. • The female is the egg.
14. Gametes are called reproductive or germ cells. The others are called somatic cells.
15. Because each gamete only has 23 chromosomes it is said to be haploid. The zygote is diploid because it has a full 46 chromosomes.
Mitosis & Meiosis • 1. Somatic (body) cells undergo mitosis. • 2. Reproductive cells (egg and sperm) undergo meiosis.
3. You make about 25 million cells per second. • 4. Mitosis refers to nuclear division.
5. Mitosis results in new cells with DNA that is identical to the original cell. Mitosis occurs in organisms undergoing growth, development, repair, or asexual reproduction.
6. Mitosis results in two daughter cells with the same genetic make-up as the parent cell. • 7. There are four phases of mitosis.
1 – prophase • 2 – metaphase • 3 – anaphase • 4 - telophase
9. After mitosis, cytokinesis begins. This is when the cytoplasm is divided in ½ and two individual cells are formed.
10. Each new daughter cell is genetically identical and diploid.
11. Between cell divisions the cell goes through interphase.
12. During interphase the cell grows, the DNA replication occurs, chromosomes begin to condense, microtubules are made, and organelles are replicated.
13. The process by which a copy of the DNA molecule is produced is called replication. Replication is semi-conservative because half of the old molecule is conserved in each new molecule.
MEIOSIS • 1. Meiosis is a type of cell division which produces four reproductive cells. • 2. These four cells are haploid. They contain ½ the number chromosomes as the parent cell.
3. Meiosis consists of two cell divisions. Meiosis I and meiosis II.
4. In meiosis I the homologous chromosomes line up next to each other and crossing over occurs. This is an exchange of segments.
5. The cell then splits into two daughter cells each with one pair of homologous chromosomes.
6. In meiosis II the two daughter cells divide again. The result is four haploid gametes with ½ the number of chromosomes as the parent cell.
7. When a male and female gamete unite in fertilization the 2 haploid gametes will make up one diploid zygote.
8. This allows for some of each parents genetic traits to be passed on to the offspring.
9. The principle of segregation states that pairs of genes are distributed between gametes during gamete formation.
Punnett Squares • 1. These are used to determine the outcome of crosses between individuals.
2. Many diseases are passed from parent to child. These are said to be inherited. A person may be a carrier of the allele causing the disease and not know it.
3. This may occur if the allele is recessive. • 4. Some diseases are sex-linked meaning the allele for the disease is carried on the sex chromosome.
5. Examples of sex-linked diseases are • Muscular dystrophy • hemophilia
DNA • 1. There are two major kinds of molecules that direct the synthesis of proteins in eukaryotic cells. • 2. RNA and DNA.
3. The study of the structure and function of DNA and RNA is called molecular genetics.
DNA • 1. Deoxyribonucleic acid. • 2. Shaped like a double helix. • 3. Contains the genetic code for an organism. • 4. Discovered by Watson and Crick.
5. DNA consists of two long strands attached by short strands. • 6. The long strands are made of sugars (deoxyribose) and phosphates.
7. The short strands are made of nitrogen-containing bases. There are four bases. • 8. Adenine and guanine (purines) • 9. Cytosine and thymine (pyrimidines)
10. The adenine and thymine always pair up together. • 11. The guanine and cytosine always pair up together. • 12. This is called base pairing.
13. Mutations are mistakes which occur in the duplication of DNA. • 14. There are two classifications of mutations.
15. Gene mutations (point mutations) are mistakes that affect individual genes on a chromosome. (sickle cell) • 16. Chromosomal mutations are mistakes that affect the whole chromosome.
17. Down Syndrome is an example of a chromosomal mutation. Results from three copies of chromosome 21.
18. Only mutations that occur in the reproductive cells can be passed on to the next generation.
