Genetics and Heredity What makes you, you and me, me. - PowerPoint Presentation

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Genetics and Heredity

What makes you, you and me, me.

Cells

The basic building blocks of who we are. We are made up of trillions of them

They provide for our bodies structure, help with nutrition and convert nutrition to energy

Cells have many different functions and duties they carry out for the body including carrying our genes and hereditary duties

The genes they carry includes our DNA

Cells Continued

Cytoplasm:

Jelly like fluid that surrounds the nucleus of the cell

Cytoskeleton:

Structural network for the cells. They are long fibers that hold the cells together. They work with cell division and allows cells to move.

Endoplasmic reticulum :

Processes the molecules made by the cells. The processed molecules are then carried both in and outside the cells.

Lysosomes and peroxisomes:

They act as the recycling center for the cell. They breakdown the bacteria and bad stuff that invades the cell and get rid of it. They also recycle and reuse any parts of the cell that are broken down.

Cells Continued

Mitochondria:

Part of the cell that changes the food we eat into energy that the cell can use to do its job.

Nucleus:

The command center of the cell telling the cell when to grow, when to mature, when to divide and when to die. It also contains the DNA.

Plasma membrane:

Outer lining of the cell. It keeps the cell separate from its environment and allows nutrients and other materials to enter and leave the cell

Ribosomes :

They process the genetics within the cell to create proteins. They are either free floating in the cytoplasm or attached to the Endothelium Reticulum.

DNA

DNA, or deoxyribonucleic acid, the hereditary material for all human beings

Every cell contains the same DNA for the individual human

DNA is contained in the cells nucleus

DNA’s information is stored as code based on 4 chemical bases, Adenine (A), Guanine(G), Cytosine (C), and Thymine (T).

Human DNA contains about 3 million bases with 99% of the bases being the same in all humans.

The order of the bases determines what information is available for building and maintaining a human being

DNA Continued

DNA forms as Base pairs, A with T and C with G. These base pairs are attached to sugar molecules and phosphate and called a nucleotide.

Nucleotides are then arranged in two long strands called a double helix. (It looks like a twisted step ladder). The base pairs look like the rungs of a ladder and the sugar and phosphates form the vertical sides of the ladder.

DNA can make reproductions of itself. Every strand of DNA serves as a pattern for making copies

These copies must be exact because when the cell divides into new cells for it to be the same and function the same as the old cell

Gene’s

Genes are made up from DNA and are the basic unit of heredity

Some genes act as instructors for the production of proteins

Genes vary in size from a few hundred DNA bases to more than 20, 000 genes

We have two copies of each gene, one we inherit from our mother and one from our father.

Most genes remain the same in all people with about 1% being different between people.

This 1% difference is what makes each and every one of us unique and have different traits.

Genes Continued

Genes are given names by scientists and researchers to make it easier to identify and track them.

Gene names include letters, a combination of letters and numbers as well as symbols

Chromosomes

The DNA, and all its base pairs, are packaged in the nucleus of the cell and look thread-like. This thread like structure is known as a chromosome

Chromosomes are not able to be seen in the cell nucleus when the cell is not dividing

When the cell is dividing the Chromosomes and DNA are visible under a microscope because they are more tightly packed and more easily seen.

Chromosomes are divided into 2 sections or arms by the centromere or constriction point.

The shorter chromosome arm is known as the “p arm”. The long arm is the “q arm”

Chromosomes continued

Chromosomes normally contain 23 pairs or a total of 46 autosomes

22 pairs are known as autosomes and they look the same in both men and women

The 23

rd

autosome is known as the sex chromosome and is different between men and women.

Women have 2 X chromosomes and men have 1X and 1Y chromosome

The 22 Chromosomes are numbered by size

Mutations, Genes and Health

A gene mutation is when a permanent change in the DNA sequence that makes up the gene

It changes the gene the sequence so that it is different than what is found in most people

Mutations come in various sizes. It can affect one base pair (also known as a building block) or it can be as large as a segment of the chromosome that contains many genes

There are two different classifications of gene mutations Hereditary Mutations and Acquired mutations

Hereditary Mutations

These mutations are inherited from either one or both parents

They stay with you for your entire life and in virtually every cell in the body

Called germline mutations because they are present in the mothers egg or fathers sperm cells

The mothers egg and fathers sperm unite, the egg becomes fertilized and DNA from both parents unite creating a new DNA for the unborn baby

If there is a mutation in the DNA, the mutation becomes a part of the baby’s DNA and part of every cell

Acquired Mutations

An acquired mutation happens only in certain cells through out the body and not in every cell

The mutation happens sometime in your body

May be caused by environmental factors such as Ultraviolet radiation from the sum, exposure to toxic chemicals

Can also happen when there is a change when the DNA is being copied during cell division.

These acquired mutations cannot be passed on to future generations unless the mutation happens in the sperm or egg cell

Other genetic mutations

Another type of genetic mutation is known as de novo or new mutations and can be either hereditary or acquired.

De Novo mutations can happen in the sperm or the egg but does not affect other cells

Or the mutation happens after the sperm and egg unite causing each new cell after division to have the mutation

Mutations continued

Most mutations that cause disease are uncommon in the general population

Mutations that happen in more than 1% of the population are called Polymorphism and are considered a normal variation in DNA

Polymorphisms are responsible for normal differences in each of us such as eye color, hair color, blood type, height, weight, body shape

Normally they have no bad effects in us but the mutations can put us at risk for getting certain illnesses and disorders

Genes, Health and Development

All of the cells in our body need the thousands of proteins to be in the right place at the right time and do their jobs correctly

If a genes instructions for handling proteins gets changed, it can cause the protein to malfunction or disappear all together

If this happens to a protein that plays a very important role in the body, normal development of the cells and the body can disrupt normal development or cause a medical condition

If this happens it is known as a genetic disorder and can be severe enough that the embryo cannot grow and survive until birth, especially in the earliest stages of development

Genes themselves DO NOT cause diseases the mutations cause a disorder so that the gene does not work right

Genes, Health and Development

Only a small percentage of mutations cause genetic disorders with no impact on development and health especially if the protein message is not changed in anyway.

Genes that can cause genetic disorders can be repaired by certain enzymes before the changed protein is produced. This repair process helps protect us all from many diseases

Genes and Health continued

We all have two copies of each gene, one from each parent. However, sometimes the number of copies varies as many as 4 or more copies

In rare occasions, one or more genes can be missing and is known as copy number variation

The extra copies of genes or missing genes in large segments of DNA can cause the activity of certain important proteins and genes that changes how the body works

Scientists have found that 10 % of DNA has changes in gene number and most of these variations don’t affect health and development

These copy number variations can affect our risk for certain diseases and response to medications

Chromosome changes and Health

We have 46 chromosomes in each cell

Any change in the number of chromosomes will cause changes in growth, development and how the body works

Changes in chromosomes numbers happens in the production of sperms and eggs, early on in the development of the baby, or in any cell after birth

Most common change is called TRISOMY meaning people have 3copies of a chromosome in each cell.

Example is Downs syndrome, when the child has 3 copies of chromosome 21 for a total of 47 chromosomes

Chromosome changes and health continued

Another example is Monosomy, which means that people have only one copy of a specific chromosome in the cell instead of two, meaning they have 45 pairs instead of 46

It is very rare but some cells have a complete extra set of chromosomes for a total of 69 chromosomes instead of 46 or even 2 extra sets for a total of 92. These situations are not ideal for living and most babies with this will die

Genetics and Disease

Your genetic make-up can give you an increased risk or likelihood of developing certain types of disease such as breast cancer, polycystic kidney disease

It does not mean you will get the disease, it means you have an increased chance of getting it. For example, if the gene changes are inherited from a parent some of the family may get it and yet others do not.

Example: changes to the BRCA1 and BRCA2 genes can make you more at risk for getting breast cancer and/or ovarian cancer. This means you would need more frequent check-ups by the doctor to make sure the disease is not developing

Scientists are looking into what the changes a small effect has on the risk of people getting certain types of diseases. The more genes that are changed, the more at risk some people are to get certain diseases such as cancer, diabetes, obesity, heart disease, mental illness

Genetics and Disease continued

Anyone who has a genetic predisposition or

suseptability

the risk of getting a disease is affected by a number of other things

The risk can be effected by a different gene variation (called a modifier)

Lifestyle factors such as foods you eat, amount of exercise, amount of sleep you get every night

Environmental factors such as being around cigarette smoke or smoking yourself, exposure to toxic chemicals in the air and water, asbestos

Changing lifestyle and environment can help keep people from getting the disease they are at risk for getting