Year 10 genes Li: students will know how diseases are inherited by genetics. I can Define what inheritance is Accurately describe the difference between a phenotype and genotype Accurately answer questions using a punnet square

Classify which are inherited, which are environment and which are both? Body mass Red-green colour blindness Cystic fibrosis. Nose shape Sickle cell anaemia Earlobe shape Intelligence Height Eye colour

Key terms to learn Somatic cell Diploid number Haploid number Gamete cell Recessive trait Dominant trait Hereditary Phenotype Genotype Allel Punnet square Homozygous (pure breed species or pure breeding) Heterozygous

Key terms Allele= One member of a pair or series of genes that occupy a specific position on a specific chromosome Dominant = gene that produces the same phenotype in the organism whether or not its allele identical; "the dominant gene for brown eyes" Recessive = gene that produces its characteristic phenotype only when its allele is identical; "the recessive gene for blue eyes" Genotype = refers to the genetic material within a cell. Phenotype = an organisms observable traits/ physical features. Heterozygous = Homozygous (pure bread) =

All human cells have 46 chromosomes, 23 pairs. Different living things will have a different amount. The chromosomes are held in the nucleus of our cells.

The chromosomes are made up of long coiled molecules of DNA. This chemical is divided into regions called genes. The DNA molecule contains four different molecules called bases. There are four different bases. Each gene is made up of a pattern of these four bases.

The four bases are: cytosine, adenine, thymine, guanine (A, T, G and C) A and T always pair. C and G always pair.

1 Which part of the cell contains DNA? ___________________________________________ ____________________________ 2 How many different bases are there in DNA? ___________________________________________ ____________________________ 3 Which base pairs with base C? ___________________________________________ ____________________________ 4 Which base pairs with base A? ___________________________________________ ____________________________

Dominant Or Recessive Which of the following phenotypes do you think are inherited through a dominant gene?

FERTILISATION

Gametes are the sex cells – the sperm and the egg. These cells only have 23 chromosomes.

Because each egg and sperm have a random combination of genes this causes every offspring to have a different mixture of genes. This causes VARIATION

Genes in actions Is the basic unit of hereditary. Genes are made up of DNA that contains instructions in a coded form. When these instructions are decoded they are expressed as a phenotype. Q. What are the four bases that make up the coded instructions?

Genetics…… Is the study of how genes bring about characteristics, or traits, in living things and how those characteristics are inherited. Genes are portions of DNA molecules that determine characteristics of living things. Through the processes of meiosis and reproduction, genes are transmitted from one generation to the next. All characteristics are controlled by a minimum of 2 genes. (one from mum one from dad)

Inheritance: Genes and alleles The offspring of sexual reproduction obtain one gene of each type from each parent. The different forms of a gene are called alleles. The set of all genes that specify an organism's traits is known as the organism's genome.

Genome The genome for a human cell consists of about 100,000 genes. The gene composition of a living organism is its genotype. e.g. For a person's earlobe shape, the genotype may consist of two genes for attached earlobes, or two genes for free earlobes, or one gene for attached and one gene for free earlobes.

Doman Vs. recessive Dominant = gene that produces the same phenotype in the organism whether or not its allele identical; "the dominant gene for brown eyes" Recessive = gene that produces its characteristic phenotype only when its allele is identical; "the recessive gene for blue eyes" The expressed gene is said to be dominant over the unexpressed gene, which is described as recessive.

Phenotype The expression of the genes is referred to as the phenotype of a living thing. e.g. If a person has attached earlobes, the phenotype is “attached earlobes.” If the person has free earlobes, the phenotype is “free earlobes.” Even though three genotypes for earlobe shape are possible, only two phenotypes (attached earlobes and free earlobes) are possible.

THE ALLELES FOR EYE COLOUR have a go!! B is the gene for brown eyes b is the gene for blue eyes What trait is expressed? (what is the phenotype?) Alleles: BB Bb bb

Inheritance survey

Survey

Punnet squares a type of grid that indicates all the possible outcomes of a genetic cross and can be used to determine probabilities of offspring inheriting certain characteristics for specific traits.

Probability of Inheritance The value of studying genetics is in understanding how we can predict the likelihood of inheriting particular traits. This can help plant and animal breeders in developing varieties that have more desirable qualities. It can also help people explain and predict patterns of inheritance in family lines.

One of the easiest ways to calculate the mathematical probability of inheriting a specific trait was invented by an early 20th century English geneticist named Reginald Punnet. His technique employs what we now call a Punnet square. This is a simple graphical way of discovering all of the potential combinations of genotypes that can occur in children, given the genotypes of their parents. It also shows us the odds of each of the offspring genotypes occurring.genotypes

Steps to create a punnet square Setting up and using a Punnet square is quite simple once you understand how it works. You begin by drawing a grid of perpendicular lines:

Next, you put the genotype of one parent across the top and that of the other parent down the left side. For example, if parent pea plant genotypes were YY and GG respectively, the setup would be Note: that only one letter goes in each box for the parents. It does not matter which parent is on the side or the top of the Punnet square.

Next, all you have to do is fill in the boxes by copying the row and column-head letters across or down into the empty squares. This gives us the predicted frequency of all of the potential genotypes among the offspring each time reproduction occurs. In this example, 100% of the offspring will likely be heterozygous (YG). Since the Y (yellow) allele is dominant over the G (green) allele for pea plants, 100% of the YG offspring will have a yellow phenotypeheterozygousphenotype

Allele Types Write the correct term for the following definitions 1.Organisms that have two identical alleles particular trait (TT or tt) Homozygous 2. Organisms that have two different alleles same trait (Tt) Heterozygous 3. Physical characteristic of an organism Phenotype 4. Genetic makeup of an organism (Tt) Genotype

Gene Expression Are the following sentences true or false? - Homozygous organisms are true breeding for a particular trait. False - Plants with the same phenotype always have the same genotype. False

Working out genotypes from phenotypes Pedigree charts a diagram that illustrates the inheritance pattern of characteristics for specific traits in a family tree and can be used to determine the probability of certain offspring in different generations having particular characteristics for those traits.

Inherited Diseases Beta thalassemia Beta thalassemia is a blood disorder that reduces the production of haemoglobin. Haemoglobin is the iron-containing protein in red blood cells that carries oxygen to cells throughout the body. In people with beta thalassemia, low levels of haemoglobin lead to a lack of oxygen in many parts of the body. Affected individuals also have a shortage of red blood cells (anaemia), which can cause pale skin, weakness, fatigue, and more serious complications. People with beta thalassemia are at an increased risk of developing abnormal blood clots. Beta thalassemia occurs most frequently in people from Mediterranean countries, North Africa, the Middle East, India, Central Asia, and Southeast Asia. Thalassemia put in Anastasia video

Beta thalassemia related to genetics Mutations in the HBB gene cause beta thalassemia. The HBB gene provides instructions for making a protein called beta-globin. Beta- globin is a component (subunit) of haemoglobin. Is inherited by a recessive process which means both mutated genes need to be present for an individual to show any symptoms of Beta thalassemia. You can be a carrier if you have one gene.

questions

Research task You are to research an inherited disease. You must include the following. Name of disease Is it recessive or dormant? Can you name the gene that causes the disease What are the signs and symptoms of this disease Is there any research in fixing this this disease? Are there any organisations that raise money to help individuals as well as research with this disease?

Dominant Or Recessive Which of the following phenotypes do you think are inherited through a dominant gene?

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