Write down and complete the data table below

Write down and complete the data table below

Types of Reproduction

Advantages Disadvantages

Sexual

Asexual

• Allows for genetic variation

• Can result in better species

• Requires partner

• Does not require partner

• Generally faster• Does not allow for

genetic variation

Through asexual reproduction a

clone is produced. Asexual

reproduction is usually derived

by mitosis.

ParthenogenisisAsexual Reproduction where the female produces offspring from unfertilized eggs.

WHAT IS SEXUAL REPRODUCTION?

TWO PARENTS GIVING RISE TO AN OFFSPRING THAT IS A GENETIC MIX

OF THE PARENTS.

HUMAN LIFE CYCLE

The only haploid cells in humans

are the gametes.

Angiosperm Life Cycle

Fungi Life CycleUnion of the cytoplasm of the 2 parent mycelia

Haploid nuclei contributed by the 2

parents fuse, producing diploid cells

Haploid and diploid cells may undergo mitosis but only diploid cells will undergo meiosis

Each cycle of chromosome halving and doubling contributes to genetic variation among offspring

THREE TYPES OF LIFE CYCLES

Meiosis

A reduction division, followed by fertilization ensures genetic diversity

in sexually reproducing organisms

Meiosis

• Makes gametes• Reduces a diploid cell to form multiple haploid

cells.– Each haploid cell is genetically different from the

other cells.– Each haploid cell contains a mix of half of the

genetic information of the parent cell.• Meiosis is divided into 2 divisions:

– Meiosis I and Meiosis II

Phases of Meiosis

• Step by step process where a diploid reproductive cell produces 4 haploid daughter cells.

• First up is Interphase– Same as the cell cycle

• Cell must divide 2 times in order to produce 4 haploid cells.– The 1st meiotic division makes 2 cells & then each of

these cells divides during the 2nd meiotic division producing the 4 cells total.

Meiosis 1

Homologous chromosomesThey are similar in shape & size

and the 2 chromosomes carry the same genes.

n represents the number of chromosomes in a haploid cell & 2n

for diploid cells.

Prophase I

Homologous chromosomes cross over-break & twist around each other; then connect at each other’s initial position

=recombinant chromosome

Can occur 2 to 3 times between a pair of homologous chromosomes depending on size of chromosomes & position of centromeres

Metaphase IWHAT’S DIFFERENT IN THIS METAPHASE COMPARED TO THE ONE DURING MITOSIS?

WHAT DOES INDEPENDENT ASSORTMENT MEAN?

Anaphase I

WHAT’S DIFFERENT IN THIS ANAPHASE

COMPARED TO THE ONE DURING MITOSIS?

Telophase I

AFTER CYTOKINESIS, WILL THESE CELLS BE HAPLOID OR DIPLOID? EXPLAIN

QUICK RE-CAP OF MEIOSIS I

Takes place in order to produce two cells with a single set of chromosomes each.

Why don’t the cells go through interphase again before entering prophase II ?

Random Fertilization• Adds to genetic variation arising from meiosis

– In humans, the fusion of a sperm and egg will produce a zygote with any of about 64 trillion diploid combinations.

WHERE IN MEIOSIS DOES GENETIC DIVERSITY OCCUR?

Sometimes chromosomes don’t separate the way they are

suppose to = non-disjunction

Nondisjunction (Trisomy 21) - An Animated Tutorial

PLAY VIDEO

Ex: Down’s Syndrome (aka Trisomy 21

Most common chromosome anomaly.Affects 1 in 800 births

Non-disjunction can happen with other chromosomes & all having a major impact on a child’s development

Other non-disjunction disorders

Edward’s Syndrome – Trisomy 18

Patau’s Syndrome- Trisomy 13

Turner’s Syndrome- Monsomy X

Karyotypes

• A photograph of chromosomes found in a cell (during metaphase of mitosis) arranged according to size and shape.

• The shape depends largely on the location of the centromere.

• The homologous pairs are place together.• These are usually done on unborn fetuses to

determine any chromosomal anomalies.

Methods of obtaining cells for karyotyping

Amniocentesis Chorionic villus sampling

Were these chromosomes taken from a male or female? Is there any non-disjunction? Explain your answers

Were these chromosomes taken from a male or female? Is there any non-disjunction? Explain your answers

Were these chromosomes taken from a male or female? Is there any non-disjunction? Explain your answers

Were these chromosomes taken from a male or female? Is there any non-disjunction? Explain your answers