Lifes Greatest Miracle Worksheet

LifeÕs Greatest Miracle Movie Worksheet Name: __________________________________ Please answer the following questions as you watch. This sheet will be collected at the end of the movie. What is DNA Òvery goodÓ at? -Making copies of itself What risk is there for a species that only reproduces by cloning? -they would all have the same immune system. If a parasite were to come about, everyone would be wiped out How many sperm are produced by the average human male every second? Every day? Over a lifetime? -1000, 100 million, 2 trillion The process that produces sperm and eggs is called: -miosis How many chromosomes come from each parent? -23 What are the steps of meiosis: 1. Each chromosome makes an _________exact copy of itself_____________, keeping it attached at one point. 2. They condense, creating an __x_____ - shape. 3. Now the chromosome partners get together and the two, or actually four, will __________embrace____________. 4. Big chunks carrying whole bunches of genes get ____exchanged_______ between the partners. 5. The cell divides ____twice____, each time pulling the pairs apart. 6. The final result is a sperm or egg cell with ____23__ chromosomes, half the normal number. What is the advantage of diversity within a species? -the better the odds are the someone will survive to create a new generation When does a human female produce her eggs? -as a fetus What do the support cells do with the egg? -feed the egg until it grows fat The egg is swept along the fallopian tube by ______muscular contractions__________ of the tube, as well as constant swaying of tiny cilia. 1 PBS Nova: LifeÕs Greatest Miracle Movie Worksheet Inside the fallopian tube, how long does the egg have to get fertilized? What happens if it doesnÕt? -within a few hours or it will die What are some changes that happen in the body when Òlove is in the airÓ? -signals in the brain speed up the metabolism of glucose and as a result temp rises, you sweat, heartbeat increases. In a man tissues relax causing erection (penis filled w blood) How many sperm does a typical ejaculation contain? -300 million What is the immediate danger which confronts sperm in the vagina? -death. The vagina is acidic sperm must escape or die The spermÕs first obstacle, the ______cervix______, passageway to the uterus. Most of the time itÕs locked shut, plugged with mucus that keeps bacteria and sperm out. For a few days a month, around ______ovulation_________, the mucus becomes watery and forms tiny channels that guide the sperm through. What happens to sperm in the cilia of the fallopian tubes? -the outer coating of the sperm is altered by the chemicals in a womenÕs body. Only The ones altered can get a ÒdateÓ with the egg. Only. Couple 100 could move on Underneath the cloud of cells (support cells), the egg itself is encased in a thick protein shell, called the _______zona_____________. What does the sperm need in order to be allowed through the eggÕs zona? -break through. Proteins from sperms cap must hook on precisely with proteins on eggs surface. If they match the sperm is held fast and undergoes dramatic transformations. Outer coating is shed releasing enzymes that dissolve hole in zone allowing it to push its way thru Once a sperm is inside the egg, the _______membranes_______________ of the two cells _____fuse____, and the egg draws the entire content of the sperm inside. What percent of fertilized eggs fail to develop? -50 plus percent What does the zona do once a sperm is inside? -lock out all other sperm The chromosomes of the sperm and egg approach each other and then the cell _____divides______. 2 PBS Nova: LifeÕs Greatest Miracle Movie Worksheet What is happening as the fertilized egg moves down the fallopian tube toward the uterus? -it divides over and over What happens if the cell cluster splits into two groups? -creates two embryos, identical twins After fertilization, how long does it take for the cell cluster (blastocyst) to arrive in the uterus? - 5 days The cell cluster (blastocyst) contains _____100s_____ of cells. What two things does the blastocyst have to do to survive? 1. Break out of the zona 2. Find a source of nourishment What risk does the blastocyst face after it attaches to the uterus? -no more protective coating, it could be attacked by mothers immune system as a foreign invader. White blood cells will devour it 2-week after conception, the blastocyst is about the size of a ________poppy seed______________. What is the process by which cells start to organize themselves into an embryo? -gastrolation What do the 3 layers of cells go on to form? Lower (the endoderm) Ð lungs, liver, lining of the digestive tract Middle (the mesoderm) Ð heart, muslces, bones and blood Top (the ectoderm)- nervous system, skin, hair, brain, spinal cord The brain develops from the ________neural tube__________. What happens when a gene is turned on? -tells the cell to contract a specific protein _____proteins_____ are the molecules that build your body. How does a cell turn on the right set of genes and create the right proteins? 3 PBS Nova: LifeÕs Greatest Miracle Movie Worksheet -location. One the basic body plan is established, cells know exactly what they are supposed to become. Cells talk to each other thru chemical messages. Molecules that turn genes on and read DNA Ultrasounds are typically done around ___18___ weeks. At this time, doctors can typically make out the sex. How could you tell the sex of a seven-week-old embryo? -chromosomes. Two x is a girl and a y is a boy What gene turns on the production of testosterone? -SRY A penis is created if testosterone reaches the genitals. But if there are two X chromosomes and no Y, different genes get turned on and the gonads become ____ovaries_______. When is an embryo called a fetus? -2 months after fertilization Where specifically does the fetus get its nutrients? -placenta How does a fetus get its nutrients? -umbilical cord By the __4th__ month, hard bone can be seen forming in the hand and the leg. When does a fetus begin to hear sound? -after 5 months What is the main job of the fetus during the last trimester? -to grow In the 6th month, genes in the brain order the manufacture of a fatty substance called, ____myelin________. What does myelin do? -allows nerve impulses to travel 100 times faster greatly enhancing brain power During the course of a pregnancy, by how much has the motherÕs blood supply increased? -50 percent Late in pregnancy, the baby needs ____for fat becomes so great the mother cannot keep up________. What is happening in the female body during pregnancy to aid in delivery? -uterus contracts to open cervix How wide does the cervix open? -4 inches Why are human births more dangerous than other animal births? 4 PBS Nova: LifeÕs Greatest Miracle Movie Worksheet - the human brain is 3-4 times bigger than apes brain and our pelvis is narrower to allow us to walk upright. Baby has to contort to go thru opening 5