In what ways do organisms reproduce asexually?

(4 EXs)

1. Binary fission

2. Multiple fission

3. Budding

4.Fragmentation

Hermaphroditism:

1. Both male and female organs in the same individual

2. occurs in many sessile, burrowing and/or endoparasitic invertebrates and some fish

3. most avoid self-fertilization

4. each individual produces eggs (can potentially produce twice as many offspring as dioecious species)

 sequential hermaphroditism

(1 EX)

 a genetically programmed sex change occurs with an individual organism

EX: bluehead wrasse

-          Monoecious: -         

-          Parthenogenesis: -    

(4 facts)     

1. development of an embryo from an unfertilized egg

2. avoids the energy and dangers of bringing two sexes together

3. narrows the diversity available for adaptation to new conditions

4. Amneotic parthenogenisis: egg forms by mitosis

Haplodiploidy:

( 3 facts)

1. a type of sex determination in bees, wasps, and ants

2. fertilized eggs become diploid females (queens or workers) and unfertilized eggs develop parthogenetically to become haploid males (drones)

3. queen controls whether eggs are fertilized or unfertilized

-          Gametogeneis: -    

egg formation in the ovaries

primary oocyte is located within the follicles of the ovaries

-          asexual reproduction advantages: -         

Sexual reproduction advantages:

(3 facts)

1. Produce more novel genotypes to survive in times of environmental change

2. diversity prevents extinction

3. the more variation present, the less likely to become extinct

How does Spermatogenesis occur: -         

1. with a beginning egg cell, it goes thru meiosis I, and then cytokinesis, one of the duplicated cells get more cytoplasm and the other part of the cell becomes a small useless polar body (which will die)

2. then after meiosis 2, the big ovum duplicates again and the same thing happens; one egg will get more cytoplasm and the other and results in 2 polar bodies ( which will also die)

How do oogenesis and spermatogenesis in humans differ?

-  in spermatogenesis four small same sized sperms are produced

- in oogenesis, one big egg is produced

-          Testes: -         

interstitial cells (Leydig cells):

-        

located between lobules of testis

secrete testosterone

-          scrotum: -         

-          vas deferens: -         

-          seminal vesicles: -         

passes through the penis

conducts urine and sperm (not simultaneously)

Why are human male testes not located in the abdominal cavity?

 Lower temperature of scrotum is vital to normal sperm production

Describe functions of testosterone:

Growth of the penis, sperm ducts, and glands

also

Male sexual behavior

-          Ovaries: -

(5 facts)         

female gonads

1. oocytes develop in a follicle

2. mature follicles rupture through wall of ovary

3. ovum released into the pelvic cavity

4. ~400k primary oocytes in ovaries at birth

5. only 300-400 reach maturity during “reproductive years”

 Also called oviducts

1. lined with cilia that draw the ovum into the oviduct and on to the uterus  

2. site of fertilization

-          uterus: -  

( 2 EXs of the composition)       

site of implantation

1. endometrium:  Specialized highly vascular lining of the uterus

2. myometrium: Thick smooth muscle layer of the uterus

-          myometrium:

What are the functions of estrogen and progesterone?

  Both Estrogen and Progesterone are involved in preparing the uterus to receive an embryo

-          Estrogen:

(3 facts)         

1. Development of  female accessory sex structures: oviducts, uterus and vagina

2. stimulates female reproductive activity

3. Development of Secondary sex characteristics: Bone development, Body hair, Initial development of mammary glands

Progesterone:

(3 facts)

1. secreted by the corpus luteum and the placenta

2. prepares the uterus for the fertilized egg

3. maintains the capacity of the uterus to hold the embryo and fetus

Follicular phase of the human menstrual cycle :-         

1. Day 1-13 

2. Rising blood levels of FSH(follicle stimulating hormone) and LH (lutenizing hormone)

a. Stimulates ovarian follicle growth

b. Estrogen secretion by follicles

Luteal phase of the human menstrual cycle:

(4 facts)

Corpus luteum (remnants of ovarian follicle)

1. Day 15-28

2. Develops into an endocrine gland under the influence of LH

3. Secretes progesterone and estrogen

4. Stimulates uterus to undergo changes in preparation for gestation

What stimulates ovulation?

A surge in LH and to a lesser extent, FSH which causes mature follicles to rupture and release ovum

How do negative feedback mechanisms work if fertilization does not occur?

Negative feedback involving hormones of the hypothalamus, anterior pituitary, and ovary, control the cycle

Why do changes in the uterus occur?

When fertilization does not occur, there is no need for the uterus, so the endometrium(lining of the womb) degenerates

What is the corpus luteum and its function?

(4 facts)

1. Tissue that forms after ovulation

2. secretes the hormone progesterone  (and estrogen).

3. If no pregnancy is established, the corpus luteum degenerates

4. continues to secrete the hormone if pregnancy occurs

1. Primary organs: Gonads that produce sperm, eggs and sex hormones

2. Accessory organs: Assist gonads in formation and delivery of gametes and may support embryos

(Day 1 – 5)

1. Due to low blood estrogen levels

2. Outer layer of endometrium degenerates and sloughs off

(Day 6 – 15)

blastocyst

(2 facts)

 1. Division of zygote as it travels to the uterus.

Binary Fission

(4 facts)

1. Common among bacteria and protozoa

2. The parent cell divides into two halves

3. Each grows into an individual similar to the parent cell

4. Binary fission can be lengthwise or transverse

Multiple Fission

(4 facts)

1. Nucleus divides repeatedly

2. Cytoplasmic division produces many daughter cells

3. Sporogony (Spore Formation)

4.Form of multiple fission in parasitic protozoa

Budding

(3 facts)

1. Unequal division of an organism

2. A new individual arises as a bud, an outgrowth of the parent

3. Occurs in cnidarians and several other animal phyla

Fragmentation

(2 facts)

1. Multicellular animal breaking into many fragments that become a new animal

2. Many anemones and hydroids

Bisexual Reproduction

(3 facts)

1.Most common form

2. Produces offspring from union of gametes from two genetically different parents

3. Organisms are dioecious,

Meiotic Parthenogenesis

(3 facts)

1. Haploid ovum formed by meiosis

2. Develops without fusion with male nucleus

3. Sperm may be absent or may only serve to activate development

(Day 14)

LH surge (and to a lesser extent FSH surge) causes mature follicle to rupture and release ovum