Sexual Reproduction Meiosis What is Sexual Reproduction Sexual
- Slides: 46
Sexual Reproduction & Meiosis
What is Sexual Reproduction? • Sexual Reproduction – Occurs when two different parents reproduce to form unique offspring (different from their parents and siblings).
What determines the TRAITS of the offspring? • DNA codes for all traits • The code for each trait is called a GENE • Offspring receive a randomized combination of genes from their parents • Some genes will be expressed, while others will not • All genes that are passed on from one generation to another are called HEREDITARY
What determines the TRAITS of the offspring? • Even traits that are not expressed in either parent, but are coded for in their DNA, are hereditary blond? ?
Which traits do you get? • Before we examine how and why some traits are expressed while others are not, we must first understand how traits are passed on from one generation to another • Let’s review sexual reproduction and the process of meiosis
Gametes sperm egg Woo hoo!
Zygote
Sexual Reproduction • Gametes join to form a Zygote egg DNA sperm Gametes develops into body cells Combined DNA Zygote
What does DNA do? • DNA is a nucleic acid containing 4 different nitrogenous bases (A, T, G, C) • The sequence of bases is called the GENETIC CODE! – this code tells your cells what to do and contributes to all of your physical traits • Eg. hair/eye colour, shoe size, determines if you are male or female
What does DNA do? • Scientists also believe that your DNA has an impact on how you think and how you behave.
The code Base G P S A T C P S P S Sugar Phosphate Nucleotide P P S P S P S Genetic Code C T A G C C G C T T A G G base G S G A C C P S P S P S Template Strand
Naming the DNA Chromosome Chromatin DNA with associated proteins as it is found in the nucleus.
Naming the DNA Chromosome One particular bundle of DNA (every species has it’s own number of chromosomes)
Naming the DNA Chromosome Can. One be coiled up during cell particular bundle of division. DNA (easier to move around without getting tangled up) (every species has it’s own number of chromosomes)
Naming the DNA Chromosome copy during copied cell division
Naming the DNA Sister Chromatids copy Identical chromosomes bound together by a centromere
Sorting out the DNA • Chromosomes are bundles of DNA • Every species has a different number of chromosomes How many chromosomes do humans have? 46 Chromosomes
Sorting out the DNA • If you got 46 chromosomes from your mother and you got 46 chromosomes from your father you would have… 92 Chromosomes!!
Sorting out the DNA • If you then reproduced, your offspring would get 92 chromosomes from you and 92 chromosomes from your partner… that’s… 184 Chromosomes!! See the problem?
Sorting out the DNA Question: If we combine the chromosomes from each parent during sexual reproduction, why doesn’t the chromosome number double? Answer: Gametes must have half the number of chromosomes as body cells example (not human) egg 10 10 20 sperm
Sorting out the DNA • Try these – How many chromosomes in each gamete? Gametes Zygote 23 23 39 39 12 12 46 78 24 Human Chicken Rice This means that EACH cell in your body has one copy of DNA from your mother and one copy of DNA from your father… BUT ONLY HALF OF THEIR GENES!!!!
How? • How do gametes get half the number of chromosomes? By the process of Meiosis
Homologous Chromosomes Gamete from mother Gamete from father
Homologous Chromosomes Homologous chromosomes are NOT identical, Zygote but code for the same traits Homologous chromosomes
Meiosis I Prophase I
Meiosis I Metaphase I Line up homologous chromosomes Completely unique DNA created Crossing Over
Meiosis I Metaphase I
Meiosis I Anaphase I
Meiosis I Telophase I
Meiosis II Prophase II DNA is not copied
Meiosis II Metaphase II
Meiosis II Anaphase II
Meiosis II Telophase II
Meiosis… the end result 4 unique cells created from one body cell Each cell has half the normal number of chromosomes (gametes)
Key Features of Meiosis • Meiosis I – Copy chromosomes – Line up and separate homologous chromosomes – Crossing over between homologous chromosomes • Meiosis II – Separate sister chromatids (normal cell division)
Why are you random? There are BUILT IN MECHANISMS in meiosis to create variation: • Crossing over events which generate an infinite number of new random chromosomes • Random assortment of your parents homologous chromosomes in their gametes during meiosis I and sister chromatids during meiosis II
Why are you random? Your specific combination of genes is a result of… • One of many sexual encounters on a particular day at a particular time • One of millions of sperm which meet with one of thousands of eggs
Why are you random? DNA doesn’t define you… • Your environment, choices and random chance all play a large role in your – Gene expression – Physical Development – Experiences – Health – Abilities
Identical?
Errors in Meiosis
Nondisjunction – Down Syndrome
Down Syndrome
Down Syndrome
Nondisjunction – Turner Syndrome
Nondisjunction – Turner Syndrome
- Sexual reproduction and genetics section 1 meiosis
- Section 1 meiosis
- Asexual reproduction cell division
- Asexualk
- Venn diagram of asexual and sexual
- What is the difference between mitosis and meiosis 2
- Mitosis vs meiosis
- Chapter 10 section 1 meiosis answer key
- Meiosis and mitosis
- Chapter 10 meiosis 1 and meiosis 2
- Crossing over during prophase 1
- When does meiosis take place
- Meiosis makes gametes
- Metaphase ii
- Chapter 13 meiosis and sexual life cycles
- Asexual amphibians
- Significance of sexual reproduction
- Reproduction
- Primary oocyte haploid or diploid
- Asexual or sexual reproduction
- Chapter 19 protists study guide answers
- Is mitosis asexual
- A sexual reproduction involves
- The taxonomy of the domestic dog and humans
- Blastula
- Chapter 10 sexual reproduction and genetics
- Disadvantages of sexual reproduction
- Asexual or sexual reproduction
- Chapter 10 sexual reproduction and genetics
- Sexual reproduction
- External fertilization
- Sexual reproduction
- Sexual or asexual reproduction
- Biology
- A sexual reproduction in plants
- Define sexual reproduction
- Sarcodines
- Sexual or asexual reproduction
- Mitosis vs meiosis chart
- Venn diagram of meiosis and mitosis
- Parthenogenesis asexual reproduction
- Reproduction in humans
- Type of sexual reproduction
- Sexual reproduction
- Sexual reproduction
- Fungus diagram
- Whats asexual reproduction