- AKA mitotic cell division or asexual reproduction- Chromosomes of parent cell doubles

- Cell splits in half

- New cells are identical to parent cells- Happens in regular repetitive manner- Is how single-celled organisms reproduce

- In multicellular organisms is used in growth, regeneration and healing

Mitosis in Animal Cells

- Nucleus of cell contains “blueprint”

- In cells DNA is a mass of twisted threads called chromatin

- During mitosis chromatin shortens and turns into small rod-like structures

Each organism has a certain number of chromosomes in its body cells

46 48

20

8

What do youCall a fly without wings?

Steps of Mitosis

Mitosis happens pretty fast. About 1 hour to complete a division then 16 to 20 hrs resting

Typically happens in unspecialized cells. In humans happens a lot in skin and bone marrow.

1. Resting Phase

- Time between cell divisions- The cell is growing

- More organelles, proteins, etc are being made

- Nucleus can be easily seen- By end chromosomes are replicating ( copying)

2. (Prophase) - Chromosomes become visible- Start looking like double strands

3. Metaphase

- Chromosomes line up in middle- Getting ready to split apart

4. Anaphase

- Separated copies of chromosomes migrate to opposite poles of cell- One complete copy goes to each end

5. Telophase- Cytoplasm starts to pinch in

- By end chromosomes will start looking thread-like again

- Two identical cells will be made

Mitosis in Plants

What Causes Mitosis?

1. Cell grows big and divides

2. Uncontrolled mitotic division is

CANCER-Very rapid growth

-Each cancer cell produces more cancer cells

Asexual Reproduction

- A new organism is made from a cell or cells of a SINGLE parent organism

- No special reproductive cells or organs are used

- New organism looks like original

- Offspring are genetically identical to parent

-Results in large number of offspring in short period of time

Binary Fission

- Used by unicelluar organisms (bacteria, protists)

- Mitosis results in 2 identical cells

Under favorable conditions bacteria can divide every 20 minutes

Budding in Hydra

Bud forming

- Parent divides unevenly- Bud can break off and form a new individual

- hydra, yeast, and someworms

Regeneration in Planaria-organism regrows lost body parts

-more common in simple organisms

- starfish, earthworm, planaria, and hydra

Sporulation- Usually found in fungi, algae and some protozoa

GraftingGrafting

Sexual Reproduction

- 2 Parents

- New organism is not genetically identical to parent- Advantages:

1. New individual has variations that may make it better suited for environmental changes

2. New individuals may move into new environments

Nova chapter 1: Meiosis

What are the two sexiest animals?

Body cells - All cells in an organism except except the sex cells- Contain a certain number of chromosomes

- Humans have 46 chromosomes in their body cells

Diploid Chromosome Number(2n) - Body cells

- Chromosomes found in pairs with similar structure

This chromosome came from mom

This chromosome came from dad

- The pairs are called homologous chromosomes- One came from mom, other from

dad- Each carries genes for same trait

Gametes

- Specialized sex cells produced in sex organs- Contain genetic material of mom (egg) and dad

(sperm)

- Have monoploid chromosome number (n)

- ½ the number of chromosomes of body cells - 23 chromosomes in humans

Fertilization - The fusion of the nuclei of sperm and egg

Zygote - Single cell produced when gametes fuse

- This new cell will undergo mitoticmitotic division to produce new cells that are identical to the first

Meiosis - Cell division in which gametes receive only ½ the number of chromosomes that the parent has- Number of chromosomes is reduced

- Cell divides TWICE but chromosomes only replicatereplicate once - Results in four daughter cells

Stages of Meiosis

1. - Chromosomes have already replicated-

Synapsis - Homologous chromosomes line up together in nucleus- The pairs of chromosomes

are called tetrads

Crossing OverCrossing Over- Exchange of segments between homologous chromosomes- Allows for increase variationvariation

2. - Tetrads line up a equator of cell

3.-Disjunction occurs – homologous chromosomes separate and move to opposite ends of cell - Each new cell has only half of the info

that it originally had but two copies of the half

4. - Cytoplasm splits making two daughter cells

5. - Double stranded chromosomes line up in middle of cell

6. - Chromosomes separate becoming single strands- Chromosomes move to opposite ends

7. -Cytoplasm divides again

- New cells now have monoploid number of chromosomes ( ½ what the original had )

MitosisMitosis MeiosisMeiosis

Comparison of Mitosis and Meiosis

Growth and Asexual Growth and Asexual ReproductionReproduction

Sexual ReproductionSexual Reproduction Gamete FormationGamete Formation

No Crossing OverNo Crossing Over ( no genetic variation)( no genetic variation)

Crossing over occurs Crossing over occurs (provides for genetic (provides for genetic

variation)variation)

Cells Divide OnceCells Divide Once Cells Divide TwiceCells Divide Twice

Parents and offspring Parents and offspring IdenticalIdentical

Offspring genetically Offspring genetically different from parentsdifferent from parents

Results in 2n Results in 2n chromosome chromosome numbernumber

Results in n Results in n chromosome chromosome numbernumber

Advantages to Sexual Reproduction

1. Increased variation variation increases possibility that organism will be able to adaptadapt to changes in the environment

2.

Variations may allow organisms to move into new environments

3. Make the population more varied

Sexual Reproduction in Animals - Usually involves two sexes – male and

female

Gonads - Specialized organs where gametes developOvaries - Found in

females- Produce egg (ova) – (n)

Testes - Found in males

- Produce sperm (n)

Nova chapter 2: The eggs journey Stop 440

Hermaphrodites - Contain both ovaries and testes

- Found in slow moving organisms

- Animals rarely self fertilize

- When they come in contact with other animal they both exchange sperm and eggs

Gametogenesis

- Process of making gametes in the gonads

Oogenesis - Making of egg in ovary

Only a limited number of eggs are able to be produced by a female

By birth this has already happened

This won’t happen until puberty

Contains extra yolk

These are all dud’s

Spermatogenesis

- Making of sperm in testes

- Makes four sperm each with the n chromosome number

Egg Sperm

RoundRound TadpoleTadpole

Non-motileNon-motile MotileMotile

Larger than Larger than spermsperm

Smaller than eggSmaller than egg

n number of n number of chromosomeschromosomes

n number of n number of chromosomeschromosomes

Has YolkHas Yolk No YolkNo Yolk

Fertilization- Fusion of sperm and egg to return cells to the 2n state

Nova chapter 3: The sperms journey

Embryonic DevelopmentCleavag

e

-- Zygote divides by mitosis and new cells continue to divide by mitosis- Number of cells greatly increasesCells actually get smaller until all the cells

are the same size as the cells of an adult of the organism

- The dividing cells are called an embryo

Study of embryo’s is called embryology!!!!

Nova chapter 3: The First two weeks

Gastrulation – embryo becomes indented

- Differentiation begins

- The three layers of the gastrula will become specialized and form specific tissues in the body

- It is thought that certain sections of DNA turn off and on allowing various tissues to have different functions

-this happens very early in a pregnancy and is why mothers should avoid drugs, alcohol and chemicals especially during the first trimester

Digestive and Respiratory systems

Muscles and Reproductive systems

Skin and nervous system

Nova chapter 5 and 6: The embryo takes shape & Messages in the genes

Growth -Cell numbers continue to increase

External Development

- In water

- Embryos get nourishment from yolk

- Fertilization takes place at certain times to insure optimal growth conditions- Parents usually don’t care for young- Lot of eggs increase chance of

some young surviving

External Development -Land

Food

-protectionGases diffuse through

Fluid sac

protection

Internal development- Some reptiles and fish give birth to live

young but egg just hatches inside motherMammals

- Born underdeveloped and cared for by mom for a time- Babies feed on moms milk

Uterus (aka womb) – where embryos develop inside females bodies until birth

Placenta

- Special structure in uterus

-mom’s blood vessels and babies blood vessels are in close contact-waste from embryo diffuse into mom’s blood -nutrients and oxygen diffuse into

embryo from mom

-embryo attaches to placenta by umbilical cord

Nova chapter 7: Feeding the Growing Fetus

Non-placental mammals

Marsupials -kangaroos and oppossum

-embryos born very young

-crawl from birth canal to pouch

Monotremes - Egg laying mammals- Duckbilled platypus-Egg has lots of yolk

- Babies feed on mom’s milk

Male Reproductive System

A. Testes - Gonads of male

-produce sperm

-produce hormone testosterone- Responsible for secondary sex characteristics in males

- Deep voice, body hair, musclesTestes drop into scrotum during last month

before birth. Occasionally they don’t drop and must be dropped surgically.

Testicular Cancer is one of the most common cancers for young men. Should be checked monthly. If a lump is found go to Drs and get it checked out.

2. Scrotum - Sac of skin outside body where testes are located

- Is outside of body wall to keep temperature slightly less than body temp

-optimum temp for sperm growth

3. Epididymis - Where sperm mature and are stored

4. Vas Deferens- Tube that upwards from teste to lower abdomen

- Tubes meet at urethra

Urethra - Passageway for elimination of urine and passageway for sperm

As sperm enter urethra, prostate gland, cowpers gland and seminal vesicles release fluid called semen

Ejaculation – involuntary muscle contractions that force sperm out through urethra

The Female Reproductive System

A. Ovaries -Gonads of female- Produce eggs

- Secrete female hormone estrogen- Responsible for secondary sex characteristics- Breast development, pelvis broadens, fat distribution- Important in menstrual cycle

-found in each side of lower abdomen

- All present at birth-during a lifetime no more than 500 will be released

- Each contains about 200,000 follicles (egg sacs)

Ovulation -as egg matures follicle surrounding it bursts and releases egg

-occurs first time at puberty and then about once a month-

- Egg can be fertilized for about 24 hrs

2. Fallopian Tubes (oviducts)

- Cilia filled tubes

- Place where egg will be fertilized

- Carries egg to the uterus

3. Uterus – thick walled, muscular pear shape organ

-fertilized egg attaches to wall and continues development

4. Cervix -Narrow neck of uterus

- Opens into birth canal (vagina)

Urethra - Tube that eliminates waste from body- Completely separate from reproductive system

Menstrual Cycle

-begins at puberty – 10 to 14 year old

- Controlled by hormones made by pituitary gland and ovary

-For most women occurs on 28 day cycle- Stops during pregnancy

- Stops completely during middle age(45-50) Menopause

Stages of Menstrual Cycle

1. Follicle Stage - Follicle stimulating hormone is secreted by the pituitary gland

-FSH causes follicles to develop

-usually only one develops- Developing follicle secretes estrogen

-uterus wall thickens with mucus and blood vessels-prepares uterus for pregnancy

- Last 10 to 14 days

2. Ovulation - High levels of estrogen in body cause pituitary to stop releasing FSH and start producing LH- LH reaches a certain level and egg is released ( ovulation ) - Around day 14

3. Corpus Luteum StageAfter ovulation LH causes the empty

follicle to fill with a mass of cells called the corpus luteum

- Corpus Luteum secretes hormone progesterone

-continues growth of uterus

- Prevents FSH from being released- No new egg will

develop- Lasts 10 to 14 days

4. Menstruation

- If fertilization does not occur

1. LH secretion decreases

2. Corpus Luteum breaks down and progesterone secretions decrease3. Thickened lining of uterus breaks down

4. Extra layers of uterus, unfertilized egg and a little blood pass out of body though vagina

- Lasts 3 to 5 days5. Amount of estrogen in body decreases-FSH secretion increases and new

follicle develops

Fertilization, Implantation, and Development

Fertilization - Sperm travels from vagina to cervix to uterus then into fallopian tubes

- If egg is present sperm and egg fuse becoming a 2n zygote

- Only one sperm can break through

- 5 to 10 days after fertilization embryo enters uterus

When Twins Marry Twins (LOOK OUT)

Sarah met Adam in college and they were married as soon as they graduated. At their wedding, Sarah’s identical twin sister, Emma met Adam’s identical twin brother, Ken, for the first time. Emma and Ken were married three months later. The couples kept in touch, and two years later, Sarah and Emma were delighted to discover they were both expecting. Emma’s baby Ken Jr. was born in October.

Now, Sarah is in labor and she’s worried about the child she’s about to deliver. “Why didn’t we think of this sooner?” she says. “Identical twins should never marry identical twins. Our baby is going to be a clone of Emma and Ken’s little boy.” Ken Jr. was not what most people would call an adorable baby. His parents were worried that his irritability and behavior might be due to a health problem.

As Adam walked to the hospital nursery to see their new baby, he thought about what Sarah had said.

* Will their child look just like his or her “double cousin,” Ken Jr.? What do you think? Explain using at least 3 principles or concepts of reproduction and genetics.

* Assuming that Sarah is correct, and the children will look identical, will they also have similar personalities, behavior, and attitudes? Explain .

Implantation -enzymes from embryo “digest” part of thickened uterus and embryo attaches to this spot

-gastrula forms three germ layers

-developing human is an embryo until up to about 8 weeks after this it is called a fetus- Corpus luteum continues to produce progesterone maintaining uterus

Nourishment of Embryo

- At first yolk nourishes embryo

Umbilical Cord - Attaches to belly button-brings blood to placenta

Placenta - Moms and babies blood vessels come in contact-where wastes and nutrients s are exchanged

- Moms blood and babys blood are not exchanged

-harmful things can pass from mom to baby- nicotine, alcohol, drugs, german measles

Amnion -Fluid filled sac that protects babyNova chapter 8: The Third Trimester 4:50

Ultrasound

http://health.howstuffworks.com/adam-200131.htm

Birth-gestation period – length of pregnancy

20 days for a Mouse

21 months for an elephant

- 9 Months for a human

When fetus is ready to be born1. Uterine muscles start rhythmic contractions2. Amniotic sac bursts (water breaks)

3. Cervix dialates (opens up)

From 1 to 2 cm to 11 to 12 cm

Which causes mammary gland to produce milk

4. Baby is force out head first (usually)

5. Umbilical Cord is tied and cut leaving navel

6. Afterbirth – contractions expel placenta and

amnion-during pregnancy progesterone and estrogen prepare breasts for nursing

-After birth pituitary gland releases prolactin

Premature Birth

Cesarean Section

How does the baby come out (funny)

Multiple Births

Fraternal Twins- 2 eggs released and fertilized

-Two people with DIFFERENT hereditary material develop

- May be a boy and a girl

Identical Twins - 1 egg fertilized

- Egg divides into two embryos

- Both are same sex and have same genetic material

Twins

How is a zygote formed?

Compare genetic content of zygote to genetic content of the body cells of parents.

Identify a developmental process involved in the change of a zygote into an embryo

Where does fetal development usually occur?

Identify two factors that can affect fetal development and explain how each factor affects fetal development.

REVIEW