Part 1 – Genetics

Part 1 – Genetics:

Part 1 – Genetics Unit 1 – Understanding Biological Inheritance

Good Afternoon!:

I will distribute a booklet called: Introduction to Genetics Keep this booklet safe and bring it to class with you every day – will be used as portion of unit notes Follow along with the booklet – most of the power point notes reflect the booklet information. Highlight and add in extra notes to the booklet. DO NOT COPY WORD FOR WORD! Good Afternoon!

Characteristics of living things:

One of the big questions in Biology is defining what life is. This is hard to do so biologists often focus on describing key characteristics of life. complex organized (sub atomic particles to multi-cellular organisms) made or organic compounds respond to stimuli maintain stable internal environment (homeostasis) acquire/use materials and energy grow reproduce evolve made up of cells cells divide Characteristics of living things

In the Beginning:

life began with single celled (unicellular) organisms about 3,800 million years ago. For most of history, these single celled organisms have dominated the scene completely and they are still essential to all life. Multicellular organisms, like you and I, arose much later in time when some of these unicellular organisms learned that they could be more successful if they worked together. In the Beginning

Intro to Genetics - Booklet Inheritence:

Offspring (children) inherit traits (characteristics e.g. blue eyes, brown hair) from parents Knowledge has improved breeding for certain animals/plants Mechanisms control heredity are now understood Many traits bred true and were expected to show in offspring Other traits disappeared over time Offspring showed traits not expressed by parents (e.g. brown eye parents & blue eye children) Intro to Genetics - Booklet Inheritence

Heredity:

How are traits inherited? Why do you resemble your parents? Do your siblings resemble one another? Mechanisms that control inheritance The way species reproduce has a lot to do with inheritance Heredity

Family Resemblances:

What do you already know about Genetics that allows you to explain how traits were passed on? Think about ways you look like your parents and siblings Family Resemblances

Activity: Think:

On your own Make a list of all your physical traits that closely resemble your parents’ traits (5) Make another list of traits that closely resemble your siblings’ traits (5) Make a third list of traits that are different from your parents and your siblings (5) Activity: Think

Activity: Pair:

In partners: Share these lists and discuss your findings Activity: Pair

Activity: Share:

As a class: Share some examples with the class from each list Activity: Share

Acquired or Inherited?:

Nature vs. Nurture debate - a long time. Exactly which traits and to what degree they are inherited is still not clear for some traits e.g. criminality or addictive personality Sometimes we blame genetics for things that have nothing to do with genes Parents sometimes want to take credit for passing on good qualities or talents to children Acquired or Inherited?

Consider the following::

If someone is considered “accident” prone is this characteristic inherited or is it something the person acquires? If both parents have brown eyes, what colour of eyes do you think the children will inherit? If one parent lost a finger, how many fingers would their offspring (children) inherit? If someone gets into shape and gets large muscles, will their children automatically inherit large muscles without working out? Consider the following:

Acquired & Inherited traits:

Inherited Traits: Eye colour, general height, hair colour, blood type, earlobe attachment, tongue rolling, freckles, dimples, curly/straight hair, eyelash length, skin colour, face shape, eye shape, haemophilia, colour-blindness, thumb shape, hairline shape Acquired Traits: musculature, missing limbs/digits, most behaviours, most fears, conditions that result from disease or injury, being good at biology Acquired & Inherited traits

Meiosis Review:

Genes from two parents unite to form a new life Meiosis = Diminuation (Greek) – make smaller Creates Egg and Sperm cells with one half of the normal number of chromosomes (23) - Haploid Egg and Sperm unite to form a new individual with correct amount of genetic material (46) - Diploid Meiosis Review

Meiosis:

Meiosis

Haploid & Diploid:

Most cells in human body have 46 chromosomes New cells made have 46 – Mitosis (replication/exact copy) 46 normal number of chromosomes in humans – Diploid (2n) Any more or any less causes abnormalities If sperm had 46 chromosomes and fertilized egg with 46 = 92 chromosomes = cell termination Haploid & Diploid

Haploid & Diploid:

Meiosis – reduces human sex cells (sperm/eggs) to 23 chromosomes half genetic material Haploid (n) = Having half normal number of chromosomes Remember Half/Haploid both start H Haploid & Diploid

Chromosomes & Genes:

Chromosome: DNA molecule wrapped around nucleoprotein molecule in nucleus of cell. Gene: Segment of a DNA molecule that codes for one specific protein. Proteins control expression of traits of organism E.g. if enzyme Tyrosinase is absent = skin colour is white because melanin is not produced Chromosomes & Genes

Chromosomes & Genes:

Homologous Chromosomes: Chromosome pairs of same size and shape. Chromosomes & Genes

Crossing-over: Genetic Recombination:

Crossing-over: Genetic Recombination

* Crossing-over: Genetic Recombination:

During Prophase I, homologous chromosomes form pairs called a tetrad (pair of non-sister chromatids) Occurs during exchange of genetic material between non-sister chromatids New genetic combinations are produced in gametes (sex cells: sperm and egg) Allows for genetic variation among offspring Explains why we are unique and different * Crossing-over: Genetic Recombination

Chromosomes & Genes:

Each somatic (body cell) has pairs of homologous chromosomes Human cells – 46 chromosomes in nucleus each cell There are 23 pairs of chromosomes (half from mom, half from dad) that make up 46 chromosomes. Chromosomes & Genes

Chromosomes & Genes:

One pair out of the 23 pairs of homologous chromosomes is an exception! Pair of Sex Chromosomes Different because they do not appear homologous – not same size/length! Each of the other 22 pairs are identical in size and shape Chromosomes & Genes

*Alleles:

Allele = alternate form of a gene. Humans have eyes and eyes need a colour. The gene that codes for our eye colour has different alleles (possibilities) that code for different eye colours. e.g. brown, blue, green, hazel are all possible alleles (alternate forms) of a gene that gives us our eye colour. Homologous chromosomes each carry a gene for the same trait at the same locus (location) but can have different or the same alleles for that gene. *Alleles

*Alleles Cont’d:

There are two alleles (possibilities) for the trait of earlobes – free or attached! You will only express (show) one of them - dominant The other that is not expressed is recessive You cannot have attached and free earlobes expressed at same time! Later on, we will talk about factors that determine why some alleles are expressed over others. *Alleles Cont’d

*Alleles Cont’d :

Some alleles are dominant while others are recessive Nature determines what traits are dominant and which are recessive – scientists have figured most of these out It has been determined: Free earlobes are Dominant (always expressed) over attached earlobes (recessive) *Alleles Cont’d

*Dominant & Recessive:

Dominant: An allele responsible for a certain characteristic will always be expressed over another. Recessive: One allele that is masked (not shown) by a dominant trait. *Dominant & Recessive

Genotype & Phenotype:

Genotype: Genetic make-up of an organism Indicate genotype with letters of alphabet Upper case rep. = dominant allele (B) Lower case rep. = recessive allele (b) Letters are written in pairs (BB, Bb, bb) because alleles on homologous chromosomes also occur in pairs (one on each chromosome) Genotype & Phenotype

*Dominant & Recessive:

Example: More than one allele is possible for certain characteristics (e.g. hair colour) Brown hair is dominant to blonde hair Brown = B Blonde = b *Dominant & Recessive

Genotype & Phenotype:

Phenotype: What is actually expressed (visible/shown) from your genetic make-up. Can be the same as the Genotype but NOT always! Individual with blue eyes Individual with attached earlobes Individual with blonde hair Genotype & Phenotype

*Carrier:

Someone who does not visibly express a trait in their Phenotype but does in their Genotype You may not show this trait but you are carrying it so you can pass it down to offspring Carry the recessive trait and would not know it because it is not expressed and the dominant trait will show above all *Carrier

*Carrier Cont’d:

Carrier Example: An Individual who has one allele for brown hair (B) and one allele for blonde (b). What is their Phenotype and Genotype? Phenotype = Brown Hair Genotype = Bb Carrier for blonde hair! *Carrier Cont’d

*Genotype & Phenotype:

1. What is/are the possible genotype(s) of an individual with a phenotype of Brown hair? BB or Bb – not sure which one because brown will always show! Just because the individual has brown hair does not necessarily mean that both of their alleles are dominant. The individual may carry the allele for blonde hair (b) – who knows? He/She could be: BB – Homozygous Dominant (B) Bb – Heterozygous (b) *Genotype & Phenotype

*Homozygous & Heterozygous:

Homozygous = individual has two of the same genes for a trait (BB or bb) Heterozygous = individual has two different genes for a trait (Bb) Note: We always write the dominant letter first! (Bb) *Homozygous & Heterozygous

*Homozygous & Heterozygous:

An individual is said to be: Homozygous Dominant if both alleles code for the dominant trait – BB Homozygous Recessive if both alleles code for the recessive trait – bb Heterozygous if both alleles are different - Bb *Homozygous & Heterozygous

Eye Colour:

Gene that determines eye colour has several alternate forms or alleles brown, blue, hazel, green etc. Individual can have the same allele for the gene (e.g. blue eyes) on each of the two chromosomes that make a homologous pair diagram in booklet shows a pair of homologous chromosomes having same allele for blue eyes on each. What is the Phenotype? What is the Genotype Homozygous dominant? Homozygous recessive? Heterozygous? Eye Colour

Genotype & Phenotype Examples:

In your book p.8 there are more examples of dominant and recessive traits Read through Genotype & Phenotype Examples

Activity:

Go through the table and complete the activity (5 mins) Once finished – turn page and work on “Eyes and Ears” Phenotype table (5 mins) Activity

Activity/Homework:

Meiosis and Alleles Questions 1-5 and 6 if you have time. If not finished in class – homework Homework check tomorrow Activity/Homework

Quiz: Everything to date:

Inherited/Acquired traits Meiosis review – haploid/diploid Crossing over Alleles carrier Genotypes/phenotypes Quiz: Everything to date

Mendelian Genetics:

Gregor Mendel Mendelian Genetics