Unit 11 - Reproductive

What are the 2 types of reproduction?

• asexual

• sexual

The biological process where animals transfer their genetic materials to a new generation

reproduction

The genetic contribution come from a single parent and creates genetically identical offspring (no genetic diversity)

asexual reproduction

What is fertilization?

where a haploid sex cell (n) unites to form a new diploid individual

What is gametogenesis?

The process by which gametes are produced through meiosis in sexually reproducing organisms.

What is an advantage to asexual reproduction?

less energy is required for reproduction, allowing for quicker population growth.

In what kind of environments do we typically find asexual reproduction?

Asexual reproduction is typically found in stable and unchanging environments, where the organisms can rapidly exploit resources without the need for genetic variation.

What are the 4 types of asexual reproduction?

• budding

• fission

• fragmentation/regeneration

• Parthenogenesis/virgin birth

A type of asexual reproduction where the new individual forms as an outgrowth of the old one

Budding (Ex: sponges)

A type of asexual reproduction where one individual separates into two or more individuals of equal size

fission (Ex: bacteria, anemones)

A type of asexual reproduction where the individual breaks into small pieces and each piece forms a new individual

fragmentation/regeneration (Ex: echinoderms/starfish)

A type of asexual reproduction where the individual is developed from an unfertilized egg

parthenogenesis (Ex: some reptiles, insects)

Hermaphroditism is a unique form of what kind of reproduction?

sexual reproduction

What is simultaneous hermaphroditism?

A reproductive strategy in which an individual possesses both male and female reproductive organs

What is sequential hermaphroditism?

A reproductive strategy where an individual changes sex from male to female or vice versa during its lifetime (ex: clownfish)

Protogynous

refers to a type of sequential hermaphroditism where an individual starts as a female and later changes to a male.

Protoandrous

refers to a type of sequential hermaphroditism where an individual starts as a male and later changes to a female.

Sexual reproduction increases genetic diversity through which 3 mechanisms?

1. genetic recombination

2. independent assortment

3. random fertilization

A type of sexual reproduction where the alleles of the parents mix into new combinations within chromosomes

Genetic recombination is the process whereby genetic material is physically mixed during meiosis, resulting in offspring with variations of parental traits.

A type of sexual reproduction where there is a random combination of maternal and paternal chromosomes in the gamete nuceli

is known as independent assortment.

A type of sexual reproduction where fertilization occurs from genetically different individuals

random fertilization

During spermatogenesis, each diploid parent produces ____ haploid sperm cells

four

Which part of the sperm contains enzymes that penetrate the ova?

acrosome

Which 3 hormones control spermatogenesis?

• GnRH (gonadotropin-releasing hormone)

• LH (luteinizing hormone)

• FSH (follicle stimulating hormone)

female are born with a finitie number of primary oocytes and are held dormant during which phase of meiosis until puberty?

prophase I

What is zona pellucida?

The zona pellucida is a glycoprotein membrane surrounding the plasma membrane of an oocyte, serving as a protective layer.

Which hormone stimulates one follicle to develop (complete meiosis I) during oogenesis?

FSH

Which hormone triggers ovulation?

Luteinizing hormone (LH)

Which hormone stimulates the growth and development of the oocyte?

estrogen (primarily estradiol)

Which hormone prepares the uterus for recieving the embryo?

Progesterone

How do birth control pills work?

increases estrogen levels to prevent the release of LH to prevent ovulation

Fusion of egg and sperm outside the body, usually in water

external fertilization

fertilization that occurs inside the female body

internal fertlization

what is the first step of fertilization at the cellular level?

sperm contacts the zona pellucida of the ovum

what happens during the acrosome reaction?

the sperm releases hydrolytic enzymes that digest the zona pellucida

what occurs when sperm an egg membranes meet?

their plasma membranes fuse

what is the fast block to polyspermy?

membrane depolarization of the egg immediately prevents additional sperm from entering

What happens after membrane fusion?

the sperm nucleus enters the ovum

what triggers the slow block to polyspermy?

A Ca2+ release inside the egg

What pathway is activated by Ca2+ release?

The IP3-Ca2+ signaling pathway

what does the slow block to polyspermy do?

causes separation and hardening of the zona pellucida (fertilization membrane forms)

what is polyspermy?

fertilization of an egg by multiple sperm which is prevented by fast and slow blocks

how is species-specific fertilization ensured?

specific binding between sperm and egg surface molecules (eg: zona pellucida proteins)

Oviparous

a type of internal fertilization where the organisms lay eggs, with embryos developing outside the mother's body.

Viviparous

a type of reproduction (internal fertilization) where the offspring develop inside the mother's body and are born live.

Ovoviviparous

a type of reproduction (internal fertilization) where eggs develop within the mother's body but hatch shortly before or during birth, resulting in live young.

What happens once a cell has been fertilized?

Cleavage produces a multicellular zygote called a morula

Which part of the morula divides quickly and which part divides slowly?

the animal pole divides quickly and the vegetal pole divides slowly

A morula divides into a hollow sphere of a single layer of cells called what?

a blastula

What determines holoblastic cleavage from meroblastic cleavage?

The complete or partial division of the egg during early development. Holoblastic cleavage (complete cleavage) occurs in eggs with little yolk, whereas meroblastic (incomplete cleavage) cleavage occurs in eggs with a large amount of yolk.

Which organisms undergo meroblastic cleavage?

birds and fish

What is a totipotent cell?

A cell that has the potential to differentiate into any type of cell in an organism

What is mosaic/determinate development?

each blastomere has a predetermined and restricted fate - commonly observed in protostomes

What is regulative/indeterminate development?

blastomeres totipotency up to a certain point (16-64 cell stage) - commonly observed in deuterostomes

What occurs in cell development after cleavage?

gastrulation

Where does gastrulation occur?

at the vegetal pole

Gastrulation leads to the formation of what 3 germ layers?

ectoderm, mesoderm, endoderm

During gastrulation, invagination at the blastopore forms the early gut lined with endoderm. What is this called?

archenteron

Which animals form all 3 germ layers?

diploblastic animals

where does mesoderm differentiation occur in protostomes?

near the blastopore

How does the coelom form in protostomes?

by a split in the mesoderm (schizocoelom)

What does '“schizocoelom'“ mean?

coelom formed by splitting of the mesoderm tissue

What develops first in protostomes?

the mouthis formed first before the anus.

where does mesoderm originate in deutrostomes?

from outpocketings of the archenteron (primitive gut)

how does the coelom form in deutrostomes?

from space within outpocketings (enterocoelom)

what does “enterocoelom” mean?

coelom formed from the outpocketings of the gut

what develops first in deuterostomes?

the anus

What are the key differences between protostomes and deuterostomes?

• protostomes: mouth first, schizocoelom, mesoderm near blastopore

• deuterostomes: anus first, enterocoelom, mesoderm from archenteron

In cell development, what happens after gastrulation?

organogenesis

How does organogenesis differ from gastrulation?

cells can undergo apoptosis in organogenesis

What is apoptosis?

programmed cell deathw

Organogenesis begins with __________

neurulation (neural crest formation)

What is the order of formation of the neural crest?

1. neural plate formation

2. formation of neural tube

3. somite formation

Where does the CNS develop from?

the neural tube

During neural crest formation, what do somites develop into?

vertebrae, ribs and associated muscles

True or False

Notochord is a temporary structure in vertebartes

true

What is the last stage of cell development?

metamorphosis