objective: you will be able to draw the early stages of development. do now: read...
TRANSCRIPT
Objective: You will be able to draw the early stages of development.
Do Now:• Read “Fertilization” on p. 1016
• Define fertilization
• Define Zygote
Fertilization
• Meiosis creates sex cells with a monoploid number of chromosomes
• When a sperm and an egg unite it restores the diploid number of chromosomes
• The new cell that is formed is called a zygote
Cleavage
• The first few divisions after fertilization are called cleavage
• Is the cell division done by mitosis or meiosis?
• Cleavage ends up creating a hollow ball of cells called the blastula
Activity
• We will be viewing the stages of cleavage in an animal under the microscope.
• Begin viewing the slide under the microscope
• You will need to find the following stages:-Zygote -Two cell -Four cell -morula -blastula -gastrula
• For each stage draw what you see in your notebook
Fertilization
• External fertilization is when the egg and sperm unite outside the female– Ex. Fish and frogs
• Internal fertilization is when the egg and sperm unite inside the female– Ex. Reptiles, birds and mammals
Development
• All animals need to grow in water otherwise they will dry out
• External fertilization happens in the water
• Mammals have water environment inside the female
• Reptiles and birds have internal fertilization but lay eggs– The egg contains the watery environemnt
Egg parts
• Amnion- Fluid filled and surrounds the embryo
• Allantois- Stores the waste produced by the embryo
• Yolk Sac- Stores nutrient-rich food
• Chorion- Regulates O2 going to embryo and CO2 leaving embryo
Menstrual Cycle
• Occurs in women at the onset of puberty
• Refers to the cycle in which an egg is released and the uterus is prepared for pregnancy
Concepts
• Involves three glands:– Hypothalamus– Pituitary– Ovaries
• Involves many hormones including:– Releasing hormone– FSH and LH– Estrogen
The phases• Follicular phase- Involves the thickening of the
uterus by estrogen– Makes egg grow in follicle
• Ovulation- Is the release of the egg from the ovary
– Caused by LH
• Luteal phase- Is the creation of the corpus luteum which will maintain the pregnancy
– Caused by LH
• Menstruation- Shedding of the uterus if pregnancy does not occur
Sex Hormones
• Testosterone– Cause the male secondary sex characteristics
• Estrogen– Cause the female secondary sex
characteristics
Objective: You will be able to identify and give the function of the parts of a flower.
Do Now:• Read pages 612 and 613
• For each part of the flower, write its function
• This will take you a few minutes
Male parts
• Male part is called the stamen• The stamen consist of the anther and
filament• Anther
– Carries out meiosis to make pollen– Sperm cells are inside the pollen
• Filament– Holds the anther into the air
Female parts
• Female part is called the pistil• The pistil is made of the stigma, style and
ovary• Stigma is sticky to capture the pollen• Style is a passageway to the ovary• Ovary
– Carries out meiosis to make eggs– The eggs are found within ovules
Objective: You will be able to describe the events of pollination and fertilization.
Do Now:• Read page 616
• What two things form from fertilization?
Pollination
• Pollination is the transfer of the pollen from the anther to the stigma
• If the pollen lands on a flower on the SAME plant it is called self-pollination– If it lands on a different individual then it is
called cross-pollination
• Pollinators are used to move the pollen
Fertilization
• Fertilization occurs within the ovule
• There are actually two sperm cells
• The first will fertilize the egg and form a zygote– This zygote will undergo cleavage to from
an embryo
Fertilization
• The second sperm will fertilize a 2n cell and form a 3n cell called the endosperm– The endosperm is the food source for the
embryo
• This concept of two fertilizations is called double fertilization
• It is unique to flowering plants.
After Fertilization
• The ovule itself will harden and become a seed
• The ovary itself will change and become a fruit– The fruit is used for seed dispersal
Objective: You will be able to identify and describe the parts of a seed.
Do Now:• Read page 618
• Give examples of fruits that everyone thinks are vegetables.
Seed Structure
• The embryo consists of the hypocotyl and the epicotyl– Hypocotyl becomes the root– Epicotyl becomes the leaves and upper
part of stem
• Cotyledon is used as a food source
• The seed coat protects the seed