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Transcript of Sexual Reproduction
Pass #2 How Do Humans Reproduce?
Pass #1 Male Gametes Called Sperm Cells come into contact with the female gametes the egg cell, Female Egg Cells Egg cells are constantly released by the female ovary
within the female reproduction system,
Sperm Cells The gametes carry the genetic code that is a set of instructions used in the development and functioning all living organisms. The sperm penetrates the egg. the egg is then considered fertilized . The process of fertilization produces a zygote. The single cell divided through the process of mitosis and became an embryo within 6-10 days of fertilization occurring. Mitosis Single cell Four weeks after fertilization occurs ,your heart is partially developed and began to beat. Your limbs , eyes and spine began to from, by 8 weeks your bone cells were beginning to work. You were then considered a fetus You began as a single cell. Microscopic. During these next 30 weeks all of your cells continue dividing through the process of mitosis. This would all take place in the mothers uterus. Finally after this whole process... You are introduced into the world as a baby.
From your mothers uterus,
Through the process of labor or a caesarean section. The Eggs are formed in the ovaries..
and the egg is discharged into the fallopian tubes ,(oviducts) to make its way into the uterus. The uterus is getting ready to receive the egg by building up its nutrient and blood-rich lining called endometrium. If a sperm , produced in the testis of a male comes into contact with the egg in the oviduct the egg gets fertilized and makes its way to the uterus as a zygote. The zygote attaches to the wall of the uterus and continues to grow into a blastocyst, then an embryo, then a fetus , and finally a baby. As
all know life begins as a single cell. The cell division process allows us one cell to become two, two to become three and three to become four, And it goes on until we are millions and millions of cells. It is within the nucleus that the genetic information in the form of DNA (Deoxyriobonucleic Acid) is contained that makes successive divisions possible. Cell cycle After Interphase , there are four major phases to Mitosis that take place in the following order... Phase 1: Prophase Phase 2: Metaphase Phase 3: Anaphase Phase 4: Telophase At four weeks , the limbs, eyes and spine begin to form. By nine weeks you are considered a fetus.By the end of 12 weeks all the major organs have begun their development. At this point of time the sex can be identified using ultrasound technology. Pregnancy Second Trimester (12-24 Weeks) At 16 weeks the placenta is too small to surround the baby so it moves to one side. The skeleton begins to form, the brain grows rapidly.The mother begins to feel the fetus moving. After 24 weeks most organs are developed but not yet fully developed. Pregnancy Third Trimester (Weeks 24-38) During these last three months of pregnancy, the fetus grows rapidly in overall size. It begins to move around in its amniotic acid sac, stretching and kicking. Genetics Its a branch of biology that looks at heredity , particularly how characteristics are passed on from on generation to the next. Variations are differences in characteristics caused by genetic and environmental factors. One of these Variations are a hitchhiker thumb vs. straight thumb Variation is the reason why we all don't look the same. Variation exists in all of us because of small changes in our DNA. ALLELES A region of DNA that controls a hereditary characteristic or trait. Every person has 2 copies of each gene. One from each parent. A version of a gene that codes for a particular trait. So if the traits s say eye color then the alleles of that trait could be : blue, brown, grey, green or hazel eye color. Dominance Recessive Dominant alleles (like brown eyes)override or suppress recessive alleles (like blue eyes) Dominant alleles are represented by a capital letter.
In order to get a recessive allele (like blue eyes) you must inherit two copies of that allele. Recessive alleles are represented by a lowercase letter. B b b b
Homozygous VS. Heterozygous Homozygous means a person has two copies of the same allele. They could be homozygous recessice or homozygous dominant. Heterozygous mean a person has both recessive allele and a dominant allele for a particular trait. Phenotype VS. Genotype
Phenotype- The physical appearance due to the expression of your genes. For example having blue eyes vs. brown eyes
Genotype- The specific set of alleles inherited. (BB vs. Bb VS. bb) The End!!
Thanks for watching(:
By Sabrina Kratsberg