Life Science- 5.3.8.D.2, 5.3.8.D.3

GENETICS &

CLASSIFICATION

HeredityGregor Mendel

Austrian Monk

studied garden pea plants to unveil patterns of heredity

Developed the Laws of Inheritance

Mendel noticed that traits from the pea plant parents didn’t always show up in their offspring

Heredity2 types of traits were identified:

Dominant trait – trait that appears in the offspring, offspring only needs one dominant allele from the parent to show up

Recessive trait – trait that fades in the background or may not show up in the offspring, only shows up if the offspring gets two recessive alleles from their parents

Mendel noticed that certain traits would reappear in later generations

Genes

Mendel discovered that each individual carries 2 sets of characteristics (genes)

Each offspring has two forms of a gene (one from each parent)

Genes - carry information that determines your traits.

Genes

Where are They?

Genes hang out all lined up on thread-like things called Chromosomes.The chromosomes and genes are made of

DNA which is short for deoxyribonucleic acidsChromosomes are found inside cells

Specifically in the nucleus of the cell. (the nucleus is sort of like the brain of the cell)

Genes How Do Genes Work?

Genes carry instructions for making proteins in the cell. Proteins are the building blocks for

everything in your body.

Did you know? Each cell in the human body contains

25,000 to 35,000 genes.

9/25/14

Do Now: Where are Genes found and what are they made out of ?

SWBAT- Understand how traits and characteristics are inherited from generation of organisms to the next

Genes are made of DNA and hang out all lined up on thread-like things called Chromosomes.

http://youtu.be/Mehz7tCxjSE?t=13s

Alleles

Allele - different form(s) of a gene,

responsible for hereditary variation.

Dominant trait – appears if it inherits the gene for that trait from either parent; will always be expressed and will “mask” a recessive trait. Shown by capital letter(s).

Recessive trait – appears only if it inherits that trait from both parents and can only be expressed if there are no dominant alleles present; shown by lower case letters.

AllelesGenotype –The alleles present in an organism. inherits from

its parents, the actual gene makeup represented by letters.

(Example: BB, Bb, or bb)

“Purebred”, also called Homozygous consists of gene pairs with genes that are the same. (Example: “RR” -or- “rr”)

“Hybrid”, also called Heterozygous and consists of gene pairs that are different. (Example: “Rr”) Note: The capital letter always is written first.

This is the "internally coded, inheritable information" carried by all living organisms.is

.

BB Bb bb

Phenotype – is the physical appearance of a trait.

What it looks like…Example: blue eyes or brown hair

These are the physical parts, anything that is part of the observable structure, function or behavior of a living organism.

Alleles

Red Red WhitePhenotype---------

9/30/14Do Now: What are the two kinds of genotypes

alleles ?

SWBAT- Understand how traits and characteristics are inherited from generation of organisms to the next

Punnett Square

Punnett Square - a diagram used to predict outcomes of genetic combinations. The Punnett square is a summary of every possible combination of one maternal allele with one paternal allele for each gene being studied in the cross.

Steps for Using the Punnett square:

1) One parent’s alleles (genotype) go along the top

2) The other parent’s alleles go down the side.

3) You fill in the squares like doing the communicative property of multiplication.

Punnett SquarePractice: The Parents eyes are Brown and Blue B= brown eye color b= blue eye color

Fill out the Punnett square on the right to help answer the following questions.

This organism has __50______% or ___1/2_____chance of receiving brown eyes.

This organism has __50______% or _______1/2_____ chance of receiving blue eyes.

The possible genotypes are: Bb and bb

The possible phenotypes are: Brown and BlueB= Dominant b= recessive

FM

BB Bb

b Bb bb

b Bb bb

The Cell and InheritanceKey Concepts

•What role do chromosomes play in inheritance?

•What events occur during meiosis?

•What is the relationship between chromosomes and

genes?

Key TermsMeiosis

Chromosomes and Inheritance

1903- Walter Sutton was studying chromosomes in grasshoppers.

Found that the body cells of grasshoppers have 24 chromosomes, but the sex cells only had 12 ( exactly half)

Chromosome pairsSutton observed that when a

sperm cell and an egg cell joined in fertilization the resulting fertilized egg again had 24 chromosomes.

Chromosomes exist in pairs. One chromosome in each pair came from the male parent and one came from the female parent

Genes on ChromosomesSutton knew that alleles exist in pairs in an

organism and one alleles comes from the female parent and the other from the male parent

Sutton realized that the paired alleles are carried on paired chromosomes

Chromosome theory of inheritance – genes are carried from parents to offspring on chromosomes

Meiosis

http://youtu.be/qCLmR9-YY7o?t=6s

10/3/14Do Now: Chromosomes exist in pairs, who do

they come from?

One chromosome in each pair came from the male parent and one came from the female parent

SWBAT- Understand how traits and characteristics are inherited from generation of organisms to the next

MeiosisMeiosis – the process by which the number

of chromosomes is reduced by half to form sex cells – sperm and egg

The chromosome pairs separate and are distributed to two different cells

Each of these 2 cells has half the number of chromosomes, but these chromosomes still have 2 chromatids

In the second part of Meiosis, these chromatids separate and the cells divide resulting in 4 sex cells, each with half the number of chromosomes of the original cell

Meiosis

Meiosis and Punnett squares

Punnett squares show what occurs during meiosis

When chromosome pairs separate and go into different sex cells, so do the alleles, too

10/7/14Do Now: What are chromosomes composed of

and what are Genes?

DNA and sections of a DNA molecule

Objective: SWBAT comprehend/distinguish what forms the genetic code, how a cell produce proteins and how mutations affect an organism

A Lineup of GenesHuman body cells have 23 pairs of

chromosomes or 46. Each chromosome has many genes. (around 25,000 total)

Each gene controls a trait

One chromosome pair is from the female parent and one is from the male parent

This organism is heterozygous for some

traits and homozygous for others

Each have the same gene “A and a”, b and B”

Which is Which?

What do genes control?

Objective: SWBAT comprehend/distinguish what forms the genetic code, how a cell produce proteins

Key Concepts:What forms the genetic code?How does a cell produce proteins?How can mutations affect an organism?

Key Terms:Messenger RNATransfer RNA

The DNA Connection

Main function of genes is to control the production of proteins

Genes and DNA: Chromosomes are made of DNA.

Genes are sections of a DNA molecule that codes for one specific protein. May contain several hundred to a million or more base pairs (EX: AGGTCACGAATTTTCCGG)

The Genetic Code

What is a Protein?

A protein is simply a long chain of amino acids linked together by bonds. The

backbone of amino acids form strong covalent bonds and the actual amino acids form

temporary weak bonds. The most important quality to understand about

proteins is that the position of their amino acids determine their function.

Word IntroductionsNucleotides: molecules that, when joined

together, make up the structural units of RNA and DNA.

Amino acids: A group of 20 different kinds of small molecules that link together in long chains to form proteins; building blocks of protein.

RNA: a nucleic molecule similar to DNA that delivers DNA's genetic message to the cytoplasm of a cell where proteins are made

DNA: a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses

Messenger RNA – copies code from DNA in the nucleus and carries message to ribosomes in the cytoplasm

Transfer RNA – carries amino acids to ribosome and adds them to the growing protein molecule

Types of RNA

• DNA molecule is made up of 4 different nitrogen bases Adenine (A), Thymine (H), Guanine (G) and Cytosine (C)

• The order of the nitrogen bases along a gene forms a genetic code that specifies what type of protein will be produced.

• Proteins are made of amino acids – A group of 3 base pairs codes for a specific amino acid

• Ex. CGT = alanine (an amino acid)

• The order of the 3 base code units determines the order of the amino acids and makes the different proteins

Order of Bases

10/10/14Do Now: Name the 4 nitrogen bases found in

DNA

Adenine (A), Thymine (H), Guanine (G) and Cytosine (C)

Objective: SWBAT comprehend/distinguish what forms the genetic code, how a cell produce proteins

The Role of RNA(Ribonucleic acid)

• Protein synthesis takes place on ribosome in cytoplasm (which is outside the nucleus)

• RNA acts as a messenger to take the DNA’s information in the chromosomes (in the nucleus) to the ribosomes in the cytoplasm

• RNA similar to DNA, yet different in some key ways:– single strand– ribose sugar– Bases – same - adenine, guanine and cytosine– different – uracil instead of thymine

How Cells Make Proteins(Protein Synthesis)

The steps of protein synthesis are

1. Transcription

2. Translation

10/15/14Do Now: List the 2differences between DNA and

RNA– single strand– Bases – same - adenine, guanine and cytosine– different – uracil instead of thymine

Objective: SWBAT comprehend/distinguish what forms the genetic code, how a cell produce proteins

Transcription-First Step:

1. DNA molecule unzips between base pairs

2. DNA directs the production of a strand of messenger RNA

3. To form the RNA strand – RNA bases pair with DNA bases. Guanine with Cytosine, but uracil pairs with adenine instead of Thymine

Translating the Code

Transcription-Second step:

1. Messenger RNA leaves nucleus and attaches to a ribosome in the cytoplasm

2. Messenger RNA provides the code to make the protein molecule

3. The ribosome moves along the messenger RNA strand

Translating the Code

10/16/14What carries instructions for making protein in the cell?

Genes carry instructions for making proteins in the cell.

Objective: SWBAT comprehend/explain what forms the genetic code, how a cell produce proteins and how mutations affect an organism

Translation-First Step

1. Molecules of transfer RNA attach to messenger RNA

2. Bases of transfer RNA read the message by pairing up 3-letter codes to bases of messenger RNA

3. Molecules of transfer RNA carry specific amino acids that link in a chain

4. Order of amino acids is determined by order of 3-letter code on messenger RNA

Translating the Code

Translation-Second step

1. Protein molecule grows longer as each transfer RNA adds an amino acid

2. When done the transfer RNA is released into the cytoplasm and can pick up another amino acid

3. Each transfer amino acid picks up the same type of amino acid

Translating the Code

Translating the CodeSummarized

1- Messenger RNA Production

2- Messenger RNA attaches to a Ribosome

3- Transfer RNA attaches to Messenger RNA

4-Protein Production continues

1&2- Transcription

3&4- Translation

10/21/14What part of the Cell does Transcription take

place and where does Translation take place?

Transcription- In the Nucleus

Translation – In the cytoplasm

Objective: SWBAT comprehend/ explain how mutations affect an organism

A mutation is any change in a gene or chromosome

Mutations can cause a cell to produce an incorrect protein during protein synthesis.

As a result of a mutation, the organism’s trait or phenotype, may be different from what it normally would have been

If a mutation is in a body cell, it will not be passed on to the offspring. If it is a sex cell, it can be passed on and can affect the offspring’s phenotype

Mutations

Substitution Insertion

Deletion

Some mutations happen during DNA Replication:

A single base may be substituted for another

One or more bases may be removed from a section of DNA or new bases inserted

Some mutations happen during Meiosis:

Chromosomes don’t separate correctly

Cell can end up with too many or too few chromosomes

Cell could end up with fragments of chromosomes

Types of Mutations

Mutations introduce change in an organism and so are a source of genetic variety

Some mutations are harmful, some are helpful, and some don’t affect the organism

Whether a mutation is harmful or not depends partly on the environment

A mutation causing an albino animal in the wild would be harmful, but if the animal lived in the zoo, it would not matter

Effects of Mutations

Helpful mutations improve an organism’s chances for survival and reproductionEx. Bacteria that have mutations that have given them

resistance to antibiotics are more likely to survive and reproduce

Harmful effects of Mutations are diseases or illnesses such as Sickle cell anemia (the blood cell is misshaped) this is an example of Substitution mutation Heart disease, cancer, and Alzheimer's are due to

mutations in several genes.

Effects of Mutations

Sourceshttp://www.grasshoppercontrol.com/

http://www.todayinsci.com/11/11_10.htm

http://www.accessexcellence.org/RC/VL/GG/images/genes.gif