Asexual Reproduction. Unit: Genetic Traits & Reproduction. Sexual Reproduction Mendel and Heredity. Key Words:

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1 Unit: Genetic Traits & Reproduction Sections: Asexual Reproduction Key Words: Replication Regeneration Asexual Genetic Mitosis Budding Heredity Offspring Germination reproduction trait Microorganism Classify Embryo Spores Species Recessive Punnett F1 Heterozygous square generation Homozygous Phenotype Genotype Generation P generation Heredity Allele Inherit Dominant trait Essential Questions: (by section)(**denotes extension questions) Asexual Reproduction: - How do organisms reproduce asexually? - How is asexual reproduction different from sexual reproduction? - How similar are organisms that are produced through asexual reproduction? - How are gametes involved in sexual reproduction? - How do plants reproduce sexually? - How does sexual reproduction lead to species diversity? - Why do individuals of the same species vary in how they look, function, and behave?** - What is heredity and who first proposed it? - How do organisms inherit traits from their parents? - How do scientists predict which genes as organism will inherit? - What is meant by dominant and recessive traits? - How do human select for certain traits in some organisms? - How are the characteristics of one generation related to the previous generation?** - Why do individuals of the same species vary in how they look, function, and behave?** - How does genetic variation among organisms affect survival and reproduction?** Asexual Reproduction Two main forms of reproduction - Sexual Combines gametes (sex cells) Has 2 parents - asexual does not involve the joining of gametes (sex cells) does not involve more than one parent makes an exact clone of itself budding

2 Growth attached to the parent with hereditary material Yeast, mold, sponges Fission DNA replicates itself DNA moves to opposite ends Cell divides into 2 cells 2 identical cells are created sporulation Formation of spores Fungi, algae Regeneration The ability to replace damaged tissues Starfish, planaria benefits highly efficient produces large numbers of offspring in a short period of time downfalls eliminates/limits genetic variation reduces chances for a population to adapt to environmental stress Prokaryotic cells 31C5571FF34&first=0 - Kingdom Monera - DNA is free flowing in the cytoplasm (called chromatin or hereditary material) - Because it is a single-celled organism (selfcontained), it goes through asexual reproduction o Cyanobacteria o Bacteria - Bacteria can go through fission every 20 to 30 minutes - All identical cells from the parent - Within 24 hours, can equal the # of eukaryotic cells in the human body - formation of a diploid cell joining of 2 haploid cells (gametes) Increases diversity of traits for offspring Gives more variations to ensure survival of species No identical offspring created by the process of meiosis cells that have half the number of chromosomes as the diploid normal human cell 46 chromosomes human gamete cell 23 chromosomes

3 male human gamete (23) (sperm) + female human gamete (23) (egg) = normal human cell (46) DNA deoxyribonucleic acid Forms the strands called chromosomes Makes up genes parts of the DNA strands that code for a specific protein Phenotypes physical traits Eye color Tongue-rolling Right hand/left hand Skin tone Hair color Genotypes genetic make up coding traits Dominate and recessive traits Homozygous (same) and heterozygous (different) - once fertilization occurs mitosis allows for growth Fertilization - mechanisms differ among plant and animal kingdom - animals males deposit gametes on or near the female gamete land internally via copulation water externally because of fluid environment - plants pollination sexual reproduction among plants gymnosperms naked seeds angiosperms flowering plants male gametes on anthers pollen grains transported by wind, water, or animals female gamete is attached to stigma Heredity the passing of traits from parent to offspring

4 - genes are made up of DNA - located on chromosomes Alleles different forms of genes meiosis separates chromosome pairs gives each sex cell 1 allele for each trait Genetics the study of how traits are inherited through the actions of alleles - Gregor Mendel father of genetics Austrian monk (1822) Experimented with garden peas Thought is was possible to predict outcome of flowers Experiments with Plant Hybrids Worked with large numbers to create more accurate predictions (30,000 pea plants over 8 years) - Purebreds an organism that always produces the same traits generation to generation - Cross-pollination taking pollen off male and placing it on female reproductive organ of different plant Dominant traits A factor that dominates or covers up the other traits The trait expressed/shown Recessive traits The trait that disappears (doesn t show) Can show if recessive traits combine from both parents - Punnett square Dominant and recessive alleles are represented by letters Capital letters represent dominant traits Lowercase letters represent recessive traits Genotype o The genetic make-up of an organism Homozygous Two alleles exactly the same Ex. BB or bb Heterozygous One allele dominant and one recessive Ex. Bb Phenotype o The physical expression of a particular genotype o Color, shape, physical attribute expressed Incomplete dominance - the production of a phenotype that is intermediate to those of the two homozygous parents ex. Crossing red homozygous flowers with white homozygous flowers and the offspring expressing pink flowers one allele is not able to be dominant over the other Multiple alleles - a trait controlled by more than two alleles - ex. Blood type in humans A, B, O A & B are both dominant O is recessive Possible phenotypes: o A could have AA or AO o B could have BB or BO o AB only AB o O only OO

5 Polygenic inheritance - when a group of gene pairs acts together to produce a single trait eye color fingerprints height weight body build shapes of features skin color - not limited to humans, plants have traits controlled by polygenic inheritance - genes may influence a small amount but creates the variety that is expressed many different skin tones in ethnic grouping many different shades of blue eyes many different shades of brown hair Recessive Genetic Disorders - Sickle-cell anemia homozygous recessive red blood cells are sickle-shaped instead of a disc-shape cannot deliver enough oxygen to cells of body cannot move through vessels easily usually found in tropical areas heterozygous carriers do not express the trait but are known to be resistant to malaria - Cystic fibrosis Homozygous recessive Thick mucus in areas of the lungs and digestive tract Builds up in lungs and makes it hard to breathe Reduces the flow of digestive enzymes to break down food Mostly Caucasians Sex determination - x and y chromosomes - females produce eggs with only x chromosome - males produce sperms with x or y chromosome Sex linked disorders - color-blindness linked to x chromosome - more males with color blindness than females all sexes have x chromosome more chances to pass on trait - sex-linked gene an allele inherited on a sex chromosome - hemophilia an allele inherited on the x chromosome Pedigrees - a tool for tracing the occurrence of a trait in a family (see example below)