Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: Meiosis

MEIOSIS 11-4 Making gametes…

Planaria animation: Family Remember: CHARACTERISTICS OF LIVING THINGS ALL LIVING THINGS __________ REPRODUCE

Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: Meiosis Asexual Reproduction: Producing offspring by a single parent without combining genes from another individual. The offspring are clones of the parent.

ASEXUAL REPRODUCTION Bacteria reproduce using __________________________________ Budding & regeneration are used by plants and animals to reproduce asexually (mitosis) Planaria animation: BINARY FISSION

ADVANTAGES OF ASEXUAL REPRODUCTION Can make offspring faster More energy efficient, no sperm and egg cells Don’t need a partner

DISADVANTAGES OF ASEXUAL REPRODUCTION ALL ALIKE Species CAN’T change and adapt One disease can wipe out whole population

Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: Meiosis Asexual Reproduction: Producing offspring by a single parent without combining genes from another individual. The offspring are clones of the parent. -No sperm and egg cells, only 1 parent, use mitosis, offspring are clones.

SEXUAL REPRODUCTION Combines genetic material from 2 parents (sperm & egg) so offspring are genetically __________ from parents DIFFERENT Family image from:

Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: Meiosis Asexual Reproduction: Producing offspring by a single parent without combining genes from another individual. The offspring are clones of the parent. -No sperm and egg cells, only 1 parent, use mitosis, offspring are clones. Sexual Reproduction: Producing offspring by combining genes from 2 parents. Not identical to parents, lots of variation.

ADVANTAGES OF SEXUAL REPRODUCTION Allows for variation in population Individuals can be different Provides foundation for EVOLUTION Allow species adapt to changes in their environment

DISADVANTAGES OF SEXUAL REPRODUCTION Need to find a suitable partner -takes energy to find/court a mate Genetic recombination can allow for harmful recessive traits to re-appear Less efficient Females at a disadvantage -energy cost of carrying and rearing young

Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: Meiosis Asexual Reproduction: Producing offspring by a single parent without combining genes from another individual. The offspring are clones of the parent. -No sperm and egg cells, only 1 parent, use mitosis, offspring are clones. Sexual Reproduction: Producing offspring by combining genes from 2 parents. Not identical to parents, lots of variation. -Sperm and egg cells, 2 parents, use meiosis to create sex cells, offspring are not identical to parents.

MEIOSIS is the way… to make cells with ½ the number of chromosomes for sexual reproduction

EGG + SPERM  If egg and sperm had same number of chromosomes as other body cells... baby would have too many chromosomes! Image by Riedell

Video 1 Click the image to play the video segment 11A. Video 1 Meiosis Overview

Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: Meiosis Asexual Reproduction: Producing offspring by a single parent without combining genes from another individual. The offspring are clones of the parent. -No sperm and egg cells, only 1 parent, use mitosis, offspring are clones. Sexual Reproduction: Producing offspring by combining genes from 2 parents. Not identical to parents, lots of variation. -Sperm and egg cells, 2 parents, use meiosis to create sex cells, offspring are not identical to parents. MitosisMeiosis

MITOSIS Makes ___ cells genetically _________ to parent cell & to each other Makes __________ Used by organisms to: increase size of organism, repair injuries, replace worn out cells 2 identical 2n SOMATIC (body)

MEIOSIS Makes ____ cells genetically different from parent cell & from each other Makes _____ cells Makes ______________ Used for ____________ 4 haploid Gametes (sperm & eggs) sexual reproduction

Mom 23 chromosomes Dad 23 chromosomes You have 23 pairs of chromosomes 2 23 possible different combinations of chromosomes 70 trillion different possible offspring!!! Mathematically, this means that a SINGLE MATING PAIR of humans could produce MORE VARATIONS OF OFFSPRING THAN THE TOTAL NUMBER OF HUMANS BEINGS THAT HAS EVER LIVED!!!

Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: Meiosis Asexual Reproduction: Producing offspring by a single parent without combining genes from another individual. The offspring are clones of the parent. -No sperm and egg cells, only 1 parent, use mitosis, offspring are clones. Sexual Reproduction: Producing offspring by combining genes from 2 parents. Not identical to parents, lots of variation. -Sperm and egg cells, 2 parents, use meiosis to create sex cells, offspring are not identical to parents. MitosisMeiosis Chromosomes 1-22 (autosomes) contain genes for proteins to produce almost everything The last chromosomes determine your sex

Catalyst: How are sex cells (sperm + egg) different from body cells? Reflection: what are the main differences of sexual and asexual reproduction create a case where it is an advantage to have one or the other? Meiosis