* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 8th grade Chapter 8
Public health genomics wikipedia , lookup
Minimal genome wikipedia , lookup
Therapeutic gene modulation wikipedia , lookup
Pharmacogenomics wikipedia , lookup
Polymorphism (biology) wikipedia , lookup
Gene expression programming wikipedia , lookup
Gene expression profiling wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
X-inactivation wikipedia , lookup
Nutriepigenomics wikipedia , lookup
Genome evolution wikipedia , lookup
Epigenetics of human development wikipedia , lookup
Transgenerational epigenetic inheritance wikipedia , lookup
Human genetic variation wikipedia , lookup
Heritability of IQ wikipedia , lookup
Genetic engineering wikipedia , lookup
Biology and consumer behaviour wikipedia , lookup
Behavioural genetics wikipedia , lookup
Genomic imprinting wikipedia , lookup
Population genetics wikipedia , lookup
Genome (book) wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Genetic drift wikipedia , lookup
Hardy–Weinberg principle wikipedia , lookup
History of genetic engineering wikipedia , lookup
Quantitative trait locus wikipedia , lookup
Designer baby wikipedia , lookup
Heredity Traits 1 In this presentation you will: explore how biological traits are passed on from one generation to the next explore the processes of natural selection and selective breeding ClassAct SRS enabled. Heredity Traits 1 Genetics is the scientific study that is concerned with genes, hereditary traits and variation of organisms. In this presentation, you will cover all aspects involved in studying genetics. You will also learn about the processes of: • natural selection • selective breeding Next > Heredity Traits 1 I. DNA A. Every living cell contains DNA. 1. DNA is like a large recipe book that determines all of the characteristics that are specific to individual organisms. B. Small sections of DNA are called genes. A gene 1. Genes are like the ingredients that are needed to make up each individual recipe. 2. Each gene represents a specific protein molecule. 3. Different types of protein carry out different functions. A strand of DNA Next > Heredity Traits 1 Question 1 Which of the following statements is correct? A) An individual's DNA will help determine every one of their characteristics. B) Small sections of DNA are called genes. C) DNA is found inside every living cell. D) All of the above are correct. Heredity Traits 1 II. Genes A. Nobody on this planet will ever share exactly the same copies of DNA as yourself (unless you have an identical twin). Blonde hair Black hair B. This is because you have a unique collection of genes. C. There will be a gene (ingredient) for each characteristic (recipe) you can think of, for example, hair color, eye color or face shape. Gene A / Protein A Gene B / Protein B Next > Heredity Traits 1 Question 2 "A single gene represents a single protein. This specific protein then determines a specific characteristic, such as eye color." Is this statement true? Answer Yes or No. Heredity Traits 1 III. Genomes A. We are complex organisms with large amounts of DNA in each of our cells. To save space inside the cells, DNA is tightly coiled and grouped into 23 pairs of chromosomes. Together these are called our genome. B. Within a species (group of related organisms) each organism has the same number of chromosomes. C. However, genome size (the number of chromosomes) changes from one species to the next. D. For example a fruit fly has a genome of 8 chromosomes, whereas a dog has 78 chromosomes. A chromosome 23 chromosome pairs of the human genome 1 2 3 6 7 11 4 5 8 9 10 12 13 14 15 16 17 18 19 20 21 23 22 Next > Heredity Traits 1 III. Genetic Information – Sexual Reproduction A. You cannot choose the ingredients that make you who you are today. Father chromosome pair Mother chromosome pair B. All of your DNA, found in the nucleus of every cell, carries the entire genetic information that is needed to form every one of your characteristics. C. When organisms sexually reproduce, genetic information is passed down from each biological parent to their offspring. D. In other words, one DNA chromosome from each pair is inherited from each biological parent and the new pair will not be identical to either parent. + = Child chromosome pair Next > Heredity Traits 1 IV. Genetic Information – Asexual Reproduction A. Some individuals produce offspring without the need for a mate, and produce offspring genetically identical to itself. That is, the offspring will contain exactly the same genetic information as the parent. B. This type of reproduction is known as asexual reproduction. It is most common in plants, for example a strawberry plant that produces runners to make new plants. It does occur in some animals too (for example flatworms). C. Organisms that are identical to its parent are called clones. Next > Heredity Traits 1 Question 3 The entire DNA content of a worm is grouped into six chromosomes. This is called its genome. The worm's genome contains... A) ...all of its genetic information. B) ...none of its genetic information. C) ...half of its genetic information. D) ...genetic information for itself and another worm. Heredity Traits 1 V. Hereditary Traits A. Although with sexual reproduction DNA chromosomes are inherited from each biological parent, non-twin siblings (having the same biological parents) never look identical. B. This is because it is never certain which half of each parental chromosome pair will be passed down. C. Characteristics that are passed on from one generation to the next are called hereditary traits. For example, hair color. Generation 1 Mother Father + = Generation 2 Sibling 1 Sibling 2 + Next > Heredity Traits 1 Question 4 "Apart from identical twins, siblings do not look identical. This is because it is not certain which half of each parental chromosome pair will be inherited." Is this statement true or false? Answer True or False. Heredity Traits 1 VI. Desirable Traits A. Organisms have certain features, or traits, that make it easier for them to survive in their habitat. It may be a feature that enables them to find food, escape predators or reproduce more successfully. These are desirable or favorable traits. B. A trait that makes it more difficult for an organism to survive, for example a feature that makes it easier prey, or that reduces an organism's ability to reproduce is called an undesirable or less favorable trait. Different forms of the finch found on the Galapagos Islands The peppered moth C. The genes that control these traits are passed from parent to offspring. Next > Heredity Traits 1 VII. Natural Selection A. Over time desirable traits thrive while undesirable traits decline, due to natural selection. B. The peppered moth is a wellknown example of this. Peppered moths are either pale speckled or dark brown. C. About 100 years ago, city trees in the UK were blackened by soot from coal burning. Black moths became nine times as common as brown ones. D. When pale moths landed on the dark sooty trees, they were eaten by birds more often. The dark moths therefore lived longer and reproduced more, resulting in more dark moths. As a result of natural selection, the darker moths thrived but the pale moths declined. Next > Heredity Traits 1 VIII. Selective Breeding A. Selective breeding is used to ensure plants and animals produce offspring with the most desirable characteristics possible. Desirable B. It is achieved using three strategies: 1. isolation - a group of organisms is kept separate to prevent any new members, and so new genetic material entering the group. Less desirable 2. artificial selection - breeding is limited to those organisms that display the desirable trait. 3. Inbreeding - breeding between closely-related individuals that have the most desirable traits is encouraged. Next > Heredity Traits 1 IX. Uses of Selective Breeding A. There are many uses for selective breeding. B. Farmers use it to improve their products, for example, chickens that produce large numbers of eggs, or grow quickly for meat. C. Dogs are bred selectively for particular characteristics. For example, to be of a gentle nature to make them good household pets, or to be of an aggressive nature to make them good guard dogs. D. Plants are also produced using selective breeding methods. For example, to produce the prettiest blooms or disease resistant crops. Next > Heredity Traits 1 Question 5 "Natural selection and selective breeding both tend to favor 'desirable' genetic traits." Is this statement true or false? Answer True or False. Heredity Traits 1 Question 6 "Natural selection is a natural process. Selective breeding happens when humans control and direct breeding between plants and animals." Is this statement true? Answer Yes or No. Heredity Traits 1 X. Genetic Engineering A. Genetic engineering is the process of changing and controlling the genetic make-up of an organism. B. It firstly involves identifying the gene that controls a particular trait. Genes can then be removed and inserted into chromosomes. Gene for height C. This process has many uses, including farmers using it to try to produce the biggest and best crops possible. Next > Heredity Traits 1 In this presentation you will: explore how the characteristics of living things vary explore how characteristics are passed on through generations explore how the environment can affect the characteristics of living things ClassAct SRS enabled. Heredity Traits 1 In this presentation, you will learn about what determines the characteristics of living things. You will explore how the characteristics of living things vary, and how characteristic traits are passed on through generations. You will also see how the environment can affect the characteristic traits of living things. Next > Heredity Traits 1 I. Variation A. All living things in the world are different. B. Some living things are very different to each other, for example a worm and a parrot. C. Other living things are not so different from each other, for example a black cow and a brown cow. D. We call these differences variation. You can have variation between different species and within a species. Next > Heredity Traits 1 Question 7 What is the term given to the differences in characteristics shown by living things? A) Variables B) Variability C) Variation D) All of these Heredity Traits 1 1. Continuous variation: This is when characteristics can have any value within a certain range. For example, height, intelligence, or leaf surface area. 2. Discontinuous variation: This is when the characteristics only have a few distinct options. For example, eye color, blood group or hair color. 150 160 170 180 190 200 Height in cm Number of people A. There are two main types of variation within living things: Number of people II. Types of Variation Blue Hazel Brown Green Eye color Next > Heredity Traits 1 Question 8 This chart shows the heights of students within a class. What type of variation does it show? B) Discontinuous variation Number of people A) Continuous variation 150 160 170 180 190 200 Height in cm Heredity Traits 1 III. Genes and Variation A. The variation between different organisms is partly due to the genes they possess. B. Genes are responsible for the characteristics of all living things. There are millions of different types of genes. C. A gene is a set of complex chemical instructions that controls one small detail of how to build a living thing. Next > Heredity Traits 1 D. Living things inherit genes from their biological parents. E. This is why offspring have similar features to their parents. F. You can see how the hair color and features of this kitten are similar to that of its parent. Next > Heredity Traits 1 IV. Genes and Inheritance A. Genes are contained in the DNA of chromosomes that are found in the nuclei of cells. B. Humans have 46 chromosomes. They occur in 23 pairs. One chromosome from each pair comes from each biological parent, so we have two copies of each gene. 1 6 2 3 7 8 12 13 16 17 18 19 20 21 11 Chromosome DNA 4 5 9 10 14 Nuclei 15 23 22 C. Tucked away inside your chromosomes is the information that your body uses to make you who you are. Next > Heredity Traits 1 V. Alleles A. Some genes have different forms, these are known as alleles. B. Take hair color as an example. The alleles for red hair are different to the alleles for brown hair, and these are different to the alleles for blond hair. C. The allele combinations that you possess are responsible for your unique mix of characteristics. Next > Heredity Traits 1 VI. How do Genes Work? A. Genes normally work in pairs. 1. We have two copies of each gene. One copy comes from each biological parent. Chromosomes 2. The chances are that for some genes, the alleles we inherited from each parent are different. Alleles DNA Next > Heredity Traits 1 Question 9 Which of the following state why offspring have similar characteristics to their parents? A) They inherit genes from their parents. B) They have exactly the same alleles as both their parents. C) They are not affected by the environment. D) All of these. Heredity Traits 1 VII. How do Genes Work? A. One allele may be dominant over another. This means that the effects of some alleles may mask the effects of other alleles. 1. For example, the gene that controls the shape of your hairline has two alleles. B. People who have a widow’s peak hairline (in the shape of a downward ‘V’) possess the dominant allele. C. People who do not have a widow’s peak possess the recessive allele. Dominant Recessive Next > Heredity Traits 1 People who have a widow’s peak either have: Dominant • two copies of the dominant allele, or • one copy of the dominant allele, and one copy of the recessive allele People who don’t have a widow’s peak have two copies of the recessive allele. Recessive Dominant Recessive Next > Heredity Traits 1 Question 10 "Alleles are different forms of the same gene. For example, different alleles can code for different eye color." Is this statement true or false? Answer True or False. Heredity Traits 1 Can You Roll Your Tongue? Tongue rolling works in the same way as the widow’s peak. Dominant allele People who can roll their tongues into a U-shape possess either one or two copies of the dominant allele. People who cannot roll their tongues possess two copies of the recessive allele. Recessive allele Dominant Recessive Next > Heredity Traits 1 Question 11 "Alleles for a gene can be recessive or dominant." Is this statement true or false? Answer True or False. Heredity Traits 1 VIII. Environmental Variation A. The environment can also affect the way living things look and behave. This is known as environmental variation. B. For example, identical twins both inherit exactly the same genes which control their characteristics. However, one twin could eat more or take up weight training and become larger than the other. Next > Heredity Traits 1 C. Many of the differences between people are caused by a combination of genetic and environmental traits. D. Only very few characteristics are unaffected by the environment: 1. natural hair color 2. eye color 3. inherited diseases 4. blood groups E. Nearly every other characteristic is affected by environmental factors. These include skin color, academic and athletic ability. Next > Heredity Traits 1 Question 12 "The differences between living things of the same species are due to a combination of genetic traits and environmental conditions." Is this statement true or false? Answer True or False. Heredity Traits 1 IX. Variation in Plants A. Plants are more easily affected by environmental changes than animals. B. There are four main environmental factors that affect how well plants grow: 1. sunlight 2. soil 3. temperature 4. moisture C. A plant grown in sunlight will grow much faster and may double in size compared to a plant grown in the shade. Next > Heredity Traits 1 Question 13 Are animals more easily affected by changes in environmental conditions than plants? Answer Yes or No. Heredity Traits 1 In this presentation you will: explore how traits can be inherited explore dominant and recessive traits explore how traits in offspring can be predicted and visually represented ClassAct SRS enabled. Heredity Traits 1 In this presentation, you will explore how the characteristics of living things vary, and how characteristic heredity traits are passed on through generations. You will also see how heredity traits can be predicted in offspring when the genetic make up of the parents are known. Next > Heredity Traits 1 I. Genes and Inheritance A. Living things inherit their alleles from their biological parents. B. Genes normally work in pairs. Living things have one copy of each gene from each biological parent. C. The chances are that for some genes, the alleles that an organism inherits will be different. D. Due to the way that genes are inherited, the probability of offspring inheriting certain alleles, and therefore expressing certain traits, can be easily predicted if the parents’ alleles are known. Alleles Next > Heredity Traits 1 Question 14 "Living things inherit their genes from their biological parents." Is this statement true or false? Answer True or False. Heredity Traits 1 Question 15 Can living things have different alleles for the same gene? Answer Yes or No. Heredity Traits 1 II. Dominant and Recessive Alleles A. In a gene pair, one allele can be dominant over another. This means that the effects of some alleles mask the effects of other alleles. 1. For example, the gene that controls the shape of your little finger has two alleles. B. People who have a little finger that does not bend toward the other fingers possess two recessive alleles (ff). C. People who have a little finger that bends toward the other fingers either possess two dominant alleles (FF) or one dominant allele and one recessive allele (Ff). Dominant alleles allele Recessive F f f F F f Next > Heredity Traits 1 D. We can see that the effect of the dominant F allele masks the effect of the recessive f allele. It is due to this that the F allele is said to be dominant. Recessive alleles E. Dominant and recessive alleles are usually shown by using upper case and lower case letters. Dominant allele 1. Upper case letters are used to represent a dominant allele. 2. Lower cases letter are used to represent a recessive allele. F. Can you tell if you possess a dominant or recessive allele for finger shape? Next > Heredity Traits 1 III. Homozygous and Heterozygous A. Individuals that have two of the same alleles for a gene are said to be homozygous. B. Individuals that have two different alleles for the same gene are said to be heterozygous. Alleles f f F F F f Next > Heredity Traits 1 Question 16 If an allele is recessive... A) ... it can mask the effect of dominant alleles. B) ...it can be masked by the effects of dominant alleles. C) ...it is normally shown by using upper case letters. D) ...its effects can be seen in a heterozygous organism. Heredity Traits 1 IV. Genotype and Phenotype A. The alleles that an individual possesses within its DNA are known as its genotype. FF = Genotype B. The visible characteristics that result from the individual’s alleles is known as its phenotype. C. The inheritance of simple genetic traits that involve two different alleles of the same gene is known as monohybrid inheritance. D. We will explore monohybrid inheritance in more detail on the following screens. Bent finger = Phenotype Next > Heredity Traits 1 V. Monohybrid Inheritance A. Monohybrid inheritance is the inheritance of a single characteristic that is controlled by two alleles of the same gene; one dominant allele and one recessive allele. B. The way that alleles can be passed down from parents to offspring can be shown by using Punnett squares. Parent A B b B BB Bb b Bb bb Parent B Next > Heredity Traits 1 VI. Punnett Squares A. A Punnett square is used to demonstrate all the possible genotypes that can result from the random fusion of parent gametes. B. The alleles within the gametes of one parent are written across the top of the square. C. The alleles within the gametes of the other parent are written down the side of the square. D. The products of the different possible fusion of gametes are written in the appropriate boxes to show the different offspring genotypes that are possible. Parent A F f f Ff ff f Ff ff Parent B 50 % 50 % E. When the square is complete, the proportion of the different possible offspring genotypes (and hence the phenotypes) can be estimated. Next > Heredity Traits 1 Alleles for Wing Size in Fruit Flies Using the wing size of fruit flies, we will see how the genotypes of parent flies can be inherited by their offspring. Two alleles (A and a) control the phenotype for wing size in fruit flies. Genotype Flies with an AA genotype have a normal wing size. Flies with an Aa genotype also have a normal wing size. Flies with an aa genotype have a very small wing size. Wing phenotype AA Normal Aa Normal aa Small Allele A is dominant over allele a, because flies with an Aa genotype have normal wings. Allele a only has an effect when it is homozygous, and is therefore said to be recessive. Next > Heredity Traits 1 Monohybrid Inheritance in Fruit Flies The way that alleles can be passed from parents to their offspring can be shown in a number of ways. One of these ways is the monohybrid cross. Sticking with the wing size of fruit flies we will see how the genotypes of parent flies can be inherited by their offspring. We will cross the genotypes of a male homozygous normal winged fly (AA) with a female homozygous small winged fly (aa). A AA aa AA AA aa aa A A A a a a a Cells divide in the fruit flies’ ovaries and testis to produce gametes (cells that only have one copy of each gene). Next > Heredity Traits 1 Question 17 Allele B is dominant over allele b. If an organism is heterozygous for these alleles, will the dominant allele reflect in the phenotype? Answer Yes or No. Heredity Traits 1 Monohybrid Inheritance in Fruit Flies The male fly is AA homozygous and will produce gametes that all have the A allele. Parent phenotypes Parent genotypes The female fly is aa homozygous and will produce gametes that all have the a allele. When this pair of flies mate, their gametes fuse to form zygotes. Every zygote has two copies of each gene, one from each parent. Every zygote formed from this pair of flies will have the genotype Aa, and so will have the normal wing phenotype because A is dominant. Gamete genotypes Normal wing Small wing AA aa A a Male gametes Offspring genotype and phenotype: Female gametes a A Aa Normal wing Next > Heredity Traits 1 Monohybrid Inheritance in Fruit Flies Sticking with fruit fly wing sizes we can see how the genotypes of parent flies can be inherited by their offspring when both parents are heterozygous (Aa). Parent phenotypes Normal wing Normal wing Parent genotypes Aa Aa Gamete genotypes In this case, half of each parent’s gametes will have A alleles and half will have a alleles. There is equal chance of an A gamete joining to an A or an a gamete from the other fly. This type of cross has four possible genotype outcomes, each of which are equally likely, but there is only a 25% chance that an offspring will have the small wing phenotype. A and a A and a (Allele A is dominant to allele a) Offspring genotypes and phenotypes: Male gametes A a A AA Normal wing Aa Normal wing a Aa Normal wing aa Small wing Female gametes Next > Heredity Traits 1 Monohybrid Inheritance in Fruit Flies Male gametes From the simple cross diagrams involving dominant and recessive alleles of a gene, we have seen that the different gene combinations can produce different characteristics in offspring. A Female gametes Male gametes We can also see the probabilities of different genotypes and phenotypes of each offspring. It is important to remember that not all alleles are either dominant or recessive. Some alleles are codominant, so if an organism is heterozygous, both alleles affect the phenotype of the organism. For example, hair type. Aa Normal wing a A Female gametes a A AA Normal wing Aa Normal wing a Aa Normal wing aa Small wing Next > Heredity Traits 1 Question 18 This image shows an incomplete Punnett square for a cross concerning the tongue rolling allele. Which of the following options shows the correct offspring genotype for the square labeled X? A) TT B) Tt C) tt D) None of these Parent A T = dominant t = recessive T t T TT Tt t Tt X Parent B Heredity Traits 1 Question 19 Which of the following do Punnett squares show? A) The probabilities of the different genotypes of offspring. B) The different genotypes of offspring. C) The probabilities of the different phenotypes of offspring. D) All of the above.