Reproduction Unit An Introduction Biology I
Definition What is reproduction? Simply, making more of an organism.
Asexual vs Sexual What is the difference between asexual and sexual reproduction? Asexual – one parent gives DNA Sexual – two parents give DNA Q: Which is it if a woman goes to a sperm bank and becomes pregnant? (Sexual)
Types of Asexual Reproduction Binary fission: Single- celled organism splits in two Ex. bacteria
Types of Asexual Reproduction Budding—a bud (small replica) grows off the side of the parent and breaks off to form an independent organism Yeast hydra
Types of Asexual Reproduction Fragmentation and regeneration—a multicellular organism splits and each fragment regenerates missing body parts to form complete organisms Planaria Sea stars
Asexual Reproduction Regeneration – which of these is forming a whole, new organism and which of these is simply replacing a lost body part?
Asexual Reproduction Regeneration – more examples
Asexual Reproduction Plants - cloning Asexual – one source of DNA
Asexual Reproduction Mitosis Cell Division Used for Growth
Sexual Reproduction 2 sources of genetic material
Sexual Reproduction Fusion (joining) of two gametes, or sex cells The moment when egg and sperm (both sex cells) fuse is called fertilization The joined egg and sperm are called a zygote (a single cell) Sexual reproduction Fusion of haploid gametes – form a zygote Female – ovum Male is spermatozoon Advantage of large egg and small sperm Advantage of Sex – GENETIC VARIATION Parthenogenesis – unfertilized egg develops through mitosis – is haploid – male honey bee Also the whiptail lizards – complex form of parthenogenesis in which the chromosomes double – to make diploid zygotes – all females Hermaphorditism – each sex has both male and female parts – very efficent – Sequential hermaphrodism – when an individual reverses it’s sex – Protogynous – female first (doesn’t make sense to be male till your big enough to protect your group) Protandrous – male first (females are bigger to hold more eggs)