UNIT 1,2,3 REVIEW BIO2 FINAL

Asexual reproduction

Asexual reproduction

Produces genetically identical offspring
-binary fission (bacteria)
-simple mitosis (protists)
-fission, budding, parthenogenesis (animals)

Sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

Budding

Offspring forms within or on the parent, process is complete when it breaks free to grow on its own

Fission

an individual splits into two or more descendants

Parthenogenesis

the female produces an offspring without any genetic contribution from the male
-unfertilized eggs

Example of switching types of reproduction

-Occurs in Daphnia
-they can reproduce asexually and sexually
-when conditions of the environment worsen they switch to sexual reproduction

Advantage of asexual reproduction

-Ability to reproduce quickly
-less energy required
-no mate required

Disadvantage of asexual reproduction

-no genetic variation in offspring

Advantages of sexual reproduction

-genetic variation
-can adapt in an unstable envrionment

Disadvantage of sexual reproduction

-energetically expensive
-mate is required

Spermatogenesis

-sperm produced in testes

Epididymis

-stores sperm

3 glands of penis

Seminal vesicles, prostate gland, bulbourethral gland

Vas deferens

Long, narrow tube carrying sperm from epididymis to ejaculatory duct

What allows sperm to penetrate the barrier surrounding the eggs?

Enzyme

Oviparous

Lay an amniotic egg protected by a shell

Viviparous

Embryonic development takes place entirely within mothers body

2 functions of female reproductive system

-production and transport of eggs
-development of offspring

Where are eggs developed?

ovaries

Where are eggs fertilized?

fallopian tubes (oviduct)

Where does embryonic development take place?

uterus

What induces egg expulsion?

High levels of LH and estradiol

Lutenizing (LH)

Stimulates ovulation; testosterone synthesis

FSH (follicle stimulating hormone)

stimulates secretion of ovarian sex hormones, development of ovarian follicles, and sperm production

What type of feedback do LH and FSH have?

Positive feedback

What controls ovulation?

Hypothalamus (LH and FSH)

What happens to progesterone when fertilization occurs?

It increases to thicken the uterus wall in preparation for development and prevents the menstrual cycle

What happens to the corpus luteum if fertilization occurs?

It allows for the release of progesterone and eventually degenerates

What happens to hormones if fertilization does not occur?

They go back to normal after ovulation

What happens to the corpus luteum if fertilization does no occur?

Stops secreting progesterone and decays into corpus albicans

Fertilization

Joining of a sperm and an egg to form a diploid zygote

External fertilization

-process in which eggs are fertilized outside the female's body
-in aquatic environments

Internal fertilization

-Process in which eggs are fertilized inside the female's body
-in terrestrial animals and some aquatic animals

Can an egg be fertilized by multiple sperm?

-No, fusion must be limited to a single sperm so the egg does not receive extra chromosomes
-1st sperm to reach a receptor on the egg wins

What prevents more than one sperm from entering the egg?

-when sperm enters and eggs Ca2+ is released
-fertilization envelope prevents more than 1 sperm fro entering
-DEPOLARIZATION OF EGG PLASMA MEMBRANE

Cleavage

-Rapid cell division
-embryo size remains the same
-cells created are BLASTOMERES

Embryonic development

1. Cleavage
2. Blastula forms
3. Gastrulation
4. Organogenesis
5. Neurulation

Gastrula

-extensive and highly organized cell movements and changes in cell shape

Process of gastrulation

1. blastula hass animal pole and vegetal pole
2. invagination forms at the outer surface and eventually forms a circular opening known as blastopore
3. Surface cells fold into the interior of the embryo through the blastopore this eventually becomes the gut
4. Formation of 3 germ layers

3 germ layers

ectoderm, mesoderm, endoderm

Ectoderm

-outer covering
-nervous system
-cornea
-epidermis of skin
-epithelial lining of mouth and rectum

Mesoderm

-middle germ layer; develops into muscles, internal organs, and connective tissues
-skeletal, circulatory, lymphatic, muscular, excretory, reproductive, dermis, lining of body cavity

Endoderm

-inner gern layer
-inner lining of gut and organs
-epithelial lining of digestive tract, respiratory tract, reproductive tract, urinary tract, liver, pancreas, thyroid

Organogenesis

The division, movement, differentiation, and assembly of cells into tissues and organs

Development of the Notochord, neural tube, and somites

1. rod-like element called the notochord forms from mesodermal cells soon after gastrulation
2. Molecular signals produced in the notochord induce the dorsal ectoderm to fold
3. This folding forms the neural tube

Neural tube

tube of ectoderm that runs along the dorsal midline and gives rise to the brain and spinal chord

Somites

Mesodermal cell near the notochord
-produce important structures in the adults
-give rise to muscle, skin, and skeleton

Formation of CNS

-ectoderm along dorsal surface of embryo begins fold to form NEURAL TUBE
-parts are formed from molecular signaling
-forms brain structures
-stem cells divide to become inner and outermost layers
-gene expression to form this is controlled by TRANSCRIPTION FACTORS

What type of feedback does progesterone have on Pituitary gland?

Negative feed back, it stops the gland from secreting LH and FSH

Flowers

Produce gametes, attract pollinators, nourish embryos, and develop seeds and fruit

Seeds

Consists of an embryo, nutrient stores, and a protective coat

Fruits

Develop from the flower and contain seeds

Rhizomes

underground stems that can produce new individual plants

Corms

Modified underground stem that function in plant propagation

Apomixis

Mature seeds can form without fertilization
-asexual reproduction

Alternation of generations

1. sporophytes produce haploid spore by meiosis
2. Spores undergo mitosis to develop into gametophytes
3. Gametophytes produce sperm and eggs by mitosis
4. Gametes fuse and form diploid zygote
5. Zygote grow into diploid sporophyte by mitosis

Sepals

Leaflike parts that cover and protect the flower bud

Petals

brightly colored or scented, attract pollinator, may contain nectar gland

Stamens

Male reproductive parts
-filament and anther

Carpels

Female reproductive parts
-stigma, style, ovary

How are female gametophytes produced?

-megasporocyte (2n) divides by meiosis and forms 4 HAPLOID megaspores, THREE DEGENERATE
-surviving megaspore (n) divides by mitosis to produce HAPLOID female gametophyte EMBRYO SAC (n)
-2 synergids, 1 egg (n), 2 polar nuclei for endosperm

How are male gametophytes produced?

-inside anther, microsporocyte (2n) produces 4 haploid microspores (n) by meiosis
-microspore divide by mitosis to form haploid make gametophytes (n) POLLEN GRAINs

Fertilization in plants process

1. pollen grain lands on the stigma of a mature flower, absorbs water and GERMINATES
2. The pollen tube GROWS through the STIGMA and down the style
3. pollen tube reaches micropyle of OVULE and enters SYNERGID which DEGENERATES
4. Double fertilization takes place
-one sperm goes to EGG and forms ZYGOTE
-other sperm fuses with 2 POLAR NUCLEI which undergoes mitosis and forms ENDOSPERM

Double fertilization

-one sperm goes to EGG and forms ZYGOTE
-other sperm fuses with 2 POLAR NUCLEI which undergoes mitosis and forms ENDOSPERM

Pollination

transfer of pollen grains from an ANTHER to a STIGMA

Embryogenesis

Developmental process by which a zygote becomes a multicellular embryo

Basal

(bottom) cell is large and forms a column of cells called the suspensor that allows nutrients to travel from parent plant to embryo

Apical

Cell gives rise to the entire embryo

Cotyledons

Take up nutrients from the endosperm

Hypocotyl

Embryonic stem

Radicle

Embryonic root

What does the ovary in a plant develop into?

Develops into a fruit that protects the seeds and aids in seed dispersal

Seed coat

surrounds ovule where embryo and endosperm are developing

Functions of Fruits

-protect seeds from physical damage and seed predators
-aid in seed dispersal

Monocot

1 cotyledon, parallel venation

Dicot

2 seed leaves, branched venation

Germination

-seed takes up water
-restarts the growth and development that was temporarily suspended during seed dormancy

Meristems

-contain undifferentiated cells
-where plant growth occurs

Apical meristems

Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length.

Where does primary growth occur?

-apical meristems
-roots push downward through the soil
-shoots grow upward gaining exposure to light and CO2

Root Growth

1. Zone of cell division
2. Zone of elongation
3. Zone of differentiation

Zone of cell division

apical meristem; new cells produced (mitosis)

Zone of elongation

where cells lengthen by as much as 10 times

Zone of differentiation

Where cells differentiate into dermal, vascular, and ground tissues
-formation of xylem and phloem

Heredity

transmission of traits from one generation to the next

Variation

Demonstrated by the differences in appearance that offspring show from parent and siblings

Genetics

the study of heredity and variation

Gametes

reproductive cells

Genes

Units of heredity and are made up of segments of DNA ON chromosomes

Locus

position of a gene on a chromosome

Mitosis

cell dividing that produces identical daughter cell each with a full component of chromosomes

Meiosis

cell division the produce NON identical daughter cell, each with HALF complement of chromosomes

How many somatic cells do humans have?

23 PAIRS of chromosomes, 46 total

Homologous chromosomes

Chromosomes that have the same sequence of genes and the same structure
-2 in a pair

Sex chromosomes

Chromosomes that determine the sex of an individual
- X and Y

Autosomes

non-sex chromosomes

Diploid

2 sets of chromosomes

Haploid

Set of all individual chromosome (half)

How many polar bodies are produced during oogenesis?

3

Alleles

different versions of a gene