Topic 3 Genetics

only one parent, reproduction by mitosis or Binary fission asexual reproduction – only one parent, reproduction by mitosis or Binary fission

Biotechnology--The application of the principles of engineering and technology to the life sciences; bioengineering

body cell— (soma cell) any cell in the body that is not a sex cell

Bond--a mutual attraction between two atoms

Centriole—one of two tiny structures in an animal cell that helps form spindle fibers

Centromere—connection between two homologous chromosomes

Cytokinesis—division of the cytoplasm

Chromosome-- threadlike structure within the nucleus containing the genetic information that is passed from one generation of cells to the next

Chromatid—one side of a homologous pair of chromosomes

Clone-genetically identical organism produced by a single cell

DNA-- deoxyribonucleic acid, the hereditary material in humans and almost all other organisms

Egg-- female gamete that is haploid

Expressed—able to be seen in offspring

Gene-- sequence of DNA that codes for a protein and thus determines a trait.

genetic engineering-- process of making changes in the DNA code of living organisms

genetic recombination—recombination of genes during sexual reproduction Heredity-- the passing of traits to offspring Cell cycle-- series of events that cells go through as they grow and divide Mitosis—division of nucleus creating diploid cells

Mutation-- change in a DNA sequence that affects genetic information

Replicate— copying process by which a cell duplicates its DNA

selective breeding-- method of improving a species by allowing only those individual organisms with desired characteristics to produce the next generation

sexual reproduction-- process by which two cells from different parents unite to produce the first cell of a new organism

Sperm—male gamete that is haploid

Spindle-- fanlike microtbule structure that helps separate the chromosomes during mitosis

Subunit—parts DNA can be broken down into: Deoxyribose sugar, Phosphate, nucleic acid (A,T,G,C) All three together are called a nucleotide

Template— pattern used to make DNA, RNA, or proteins

Traits-- specific characteristic that varies from one individual to another Hw: Do crossword puzzle as bonus points on your quiz tomorrow

Heredity and Genes Heredity is the passing of genetic information from one generation to the next through reproduction. The hereditary information (DNA) is organized in the form of genes located in the chromosomes of each cell.

Chromosomes are found in the cell nuclei, and contain the DNA molecules. It is the DNA molecules that carry the genetic information of the cell.

A human cell contains many thousands of genes in its nucleus, and each gene carries a separate piece of coded information

The traits inherited by an individual can be determined by one pair of genes or by several pairs of genes. A single gene pair can sometimes influence more than one trait.

Methods of Reproduction There are two common methods of reproduction: asexual and sexual.

Asexual reproduction -- involves one parent or individual (often a single-celled organism) all the genetic instructions (genes) come from one individual or parent. Offspring are usually identical to the parent Identical genetic copies are known as clones

Bacteria Binary fission– type of mitosis

Yeast, Hydra Budding, unequal cytoplasmic division during mitosis

tubers, bulbs, runners, and grafting are types of vegetative propagation. Part of plant grows new plant

Bread Mold-- sporulation Starfish/ Planaria– fragmentation/ regeneration(new organism grows from a piece of the organism)

Parthenogenesis--- makes diploid eggs that develop into a new organism

The division of the nucleus during the M phase of the cell cycle is called ___________________. mitosis Interphase is divided into 3 phases 1. ____________ 2. ____________ 3. ___________ G1—cell growth S –DNA replication G2 – prep for mitosis

The 4 phases of Mitosis are: 1.____________ 2._____________3._____________4._____________ prophase Metaphase anaphase telophase In plant cells a _______________ forms midway of the cell. Cell plate

• Sexual reproduction-- involves two parents. Each parent produces sex cells. Sperm are the sex cells produced by the male; Egg is the sex cell produced by the female.

The offspring that results from sexual reproduction therefore receives half of its genetic information from the female parent (via the egg) and half from the male parent (via the sperm).

Chromosome Number All organisms have different numbers of chromosomes. A body cell in an adult fruit fly has 8 chromosomes: 4 from the fruit fly's male parent, and 4 from its female parent.

These two sets of chromosomes are homologous A cell that contains both sets of homologous chromosomes is said to be . diploid

The of sexually reproducing organisms contain only a single set of chromosomes, and therefore only a single set of genes. gametes These cells are . haploid

What happens during the process of meiosis? Meiosis is a process of division in which the number of chromosomes per cell is cut in through the of homologous chromosomes in a diploid cell. reduction half separation

Meiosis involves divisions, and . By the end of meiosis II, the diploid cell that entered meiosis has become 4 haploid cells. Two meiosis I meiosis II

Meiosis I Cells undergo a round of DNA replication, forming duplicate chromosomes.

Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. There are 4 chromatids in a tetrad.

When homologous chromosomes form tetrads in meiosis I, they exchange portions of their chromatids in a process called . crossing-over

fibers combinations Nuclear separates Crossing-over produces new of alleles. combinations fibers Spindle ______________ attach to the chromosomes. The fibers pull the _________________ chromosomes toward opposite ends of the cell. ____________________ membranes form. The cell ____________________ into two cells. The two cells produced by meiosis I have chromosomes and alleles that are different from each other and from the diploid cell that entered meiosis I. homologous Nuclear separates

second replication chromatids Meiosis II The two cells produced by meiosis I now enter a _____________ meiotic division. Unlike meiosis I, neither cell goes through chromosome__________________. Each of the cell’s chromosomes has 2 ____________________. second replication chromatids

haploid original center chromatids opposite four A to B Meiosis I results in two ______________(N) daughter cells, each with half the number of chromosomes as the ________________cell. C The chromosomes line up in the ______________ of cell. D The sister ____________________ separate and move toward ______________ ends of the cell. E Meiosis II results in ______________ haploid (N) daughter cells haploid original center chromatids opposite four

Gamete Formation In male animals, meiosis results in four equal-sized gametes called sperm. In many ____________ animals, only one egg results from meiosis. The other three cells, called ___________ bodies, are usually not involved in reproduction. female polar bodies

Mitosis results in the production of two genetically identical diploid cells. Meiosis produces four genetically different haploid cells.

Mitosis Cells produced by mitosis have the same number of chromosomes as the original cell. Mitosis allows an organism to grow and replace cells. Some organisms reproduce asexually by mitosis.

Meiosis Cells produced by meiosis have half the number of chromosomes as the parent cell. These cells are genetically different from the diploid cell and from each other. Meiosis is how sexually reproducing organisms produce gametes.

When a sperm and egg combine to form a new cell with a complete set of genetic instructions, a unique combination of genes results. The term for this is genetic recombination.

Hw: pg 42 Questions 1-7

The Genetic Code The inherited instructions (genes) that are passed from parent to offspring exist in the form of a chemical code called the genetic code. It is contained in the DNA molecules of all organisms. DNA molecules resemble a flexible, twisted ladder formed from many smaller repeating units

Like other large molecules of life, the DNA molecule is made of thousands of smaller sections called subunits. Each subunit has three chemical parts: a sugar a phosphate a base.

The bases of a DNA molecule are represented by the letters 2. G 3. C 4. T

The four subunits of DNA molecules are arranged in pairs, each subunit forming one side and half of one rung of the "twisted ladder."

Watson and Crick's model of DNA was a double helix, in which two strands were wound around each other.

This principle is called base pairing. Watson and Crick discovered that hydrogen bonds can form only between certain base pairs adenine and thymine guanine and cytosine. This principle is called base pairing.