Textbook Notes (378,192)
CA (167,101)
UTSC (19,203)
BIOA02H3 (153)
Chapter 42

Chapter 42 Textbook notes

7 Pages
42 Views

Department
Biological Sciences
Course Code
BIOA02H3
Professor
Andrew Mason

This preview shows pages 1-2. Sign up to view the full 7 pages of the document.
Ch 42 REPRODUCTION
42.1
How do animals reproduce without sex?
Sexual reproduction is universal in almost all organisms
Some can reproduce sexually and asexually and some can only reproduce
asexually
Offspring that are reproduced asexually are identical to each other and parents
oCan convert resources to reproduce
oDon’t have to look for a mate
oBut does not have the genetic diversity that comes with sexual
reproduction which is a disadvantage in changing environments
Animals that reproduce asexually are usually invertebrates
oAre sessile
oCan’t look for mates
oDon’t have mates around
oLive in constant environment where reproducing asexually would be
advantageous
Three ways animals reproduce asexually is by
1. budding,
2. regeneration
3. parthenogenesis
Budding and regeneration produce new individuals by mitosis
Budding—new individuals form as outgrowths or buds from older animals
oBud formed by mitosis
oBud is identical to parent
oCan grow to be as big as parent before being independent
Regeneration
oUsually thought as replacing damage tissue or lost limbs
oBut some organisms can regenerate to a new individual
oIf you cut a sea star into individual pieces then each piece will become an
individual organism
Parthenogenesis
oThe development of unfertilized eggs
www.notesolution.com
oOccurs in arthropods and some fish, amphibians and reptiles
oSome species parthenogenesis determines sex—honey bees, males come
from unfertilized eggs, females come from fertilized eggs
oParthenogenesis sometimes requires sexual behaviour—like in whiptail
lizards,
All are female
Some will act like male to stimulate another female to release eggs
Whether they act like a male or female depends on hormonal states
—when estragon levels are high it acts female, when estragon
levels go down and progesterone levels go up, then it acts male
42.2 How Do Animals Reproduce Sexually
Large portion of time and energy budgets of sexually reproducing animals goes
into mating
oMating exposes them to predators and usually takes a lot of energy, also
keeps them from doing other things like feeding and taking care of
existing offspring.
Sexual reproduction requires 2 haploid cells to come together to make a diploid
individual.
oHaploid cells are also called gametes
oGametes are formed by gametogenesis
Sexual reproduction has 3 parts
oGametogenesis (making gametes)
oMating (getting gametes together)
oFertilization (fusing gametes together)
Gametogenesis produces eggs and sperm
Gametogenesis happens in the gonads—testes in males and ovaries in females
Gametes formed in males are sperm and eggs in female
Sperm moving using a flagellum and eggs are non-motile
Gametes form from germ cell—different from other cells in the body which are
somatic cells
Germ cells are secluded in the body until gonads start to form
Then germ cells go to the gonads and by mitosis become spermatagonia and
oogonia which are diploid
They multiply by mitosis and become primary spermocytes and primary oocytes
Then through meiosis the chromosomes reduce to haploids—these become sperm
and ova
Spermatogenesis
www.notesolution.com

Loved by over 2.2 million students

Over 90% improved by at least one letter grade.

Leah — University of Toronto

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto
Saarim — University of Michigan

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan
Jenna — University of Wisconsin

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin
Anne — University of California

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California
Description
Ch 42 REPRODUCTION 42.1 How do animals reproduce without sex? Sexual reproduction is universal in almost all organisms Some can reproduce sexually and asexually and some can only reproduce asexually Offspring that are reproduced asexually are identical to each other and parents o Can convert resources to reproduce o Dont have to look for a mate o But does not have the genetic diversity that comes with sexual reproduction which is a disadvantage in changing environments Animals that reproduce asexually are usually invertebrates o Are sessile o Cant look for mates o Dont have mates around o Live in constant environment where reproducing asexually would be advantageous Three ways animals reproduce asexually is by 1. budding, 2. regeneration 3. parthenogenesis Budding and regeneration produce new individuals by mitosis Buddingnew individuals form as outgrowths or buds from older animals o Bud formed by mitosis o Bud is identical to parent o Can grow to be as big as parent before being independent Regeneration o Usually thought as replacing damage tissue or lost limbs o But some organisms can regenerate to a new individual o If you cut a sea star into individual pieces then each piece will become an individual organism Parthenogenesis o The development of unfertilized eggs www.notesolution.com
More Less
Unlock Document


Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit