Bio II Unit I Study Guide

Bio II Unit I Study Guide - 6. Location in an organism...

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6. Location in an organism Function Method by which they arise or formed Chromosome number Gamete/ sex cells/ germ cells Sperm and egg Transmit genes from one generation to next; during fertilization, male and female gametes (sperm and egg) unite, passing on genes of both parents to offspring meiotic division…. Oogenesis and spermatogenesis ½ the number of chromosomes (23) Somatic mitotic cell division Full number of chromosomes (46) Zygote: fertilized egg 7. a) Stages of embryonic development Fertilization-> cleavage-> gastrulation and morphogenesis->neurulation and organogenesis Fertilization - makes the zygote Cleavage - mitotic cell division to create a blastula Gastrulation and morphogenesis - mitotic cell division and cell differentiation to create a Gastrula Neurulation and organogenesis - mitotic cell division and cell differentiation to create an embryo b.) fertilization of a sea urchin: 1. contact of sperm and egg 2. acrosomal reaction- protein receptors in egg cell membrane “recognize” and bind to acrosomal-process protein of sperm. - fast block polyspermy 3. contact and fusion of sperm and egg membranes (cell membrane fuse) 4. sperm nucleus enters egg 5. cortical reaction- Ca++ stiumulates release of cortical enzymes out of cell result: cell membrane pulls away from from vitalline layer - fertilization envelope that leads to slow block polyspermy c.) hybridization between different species is usually prevented as specific eggs tend to be fertilized only by their specific respective sperm. It is prevented by gamete recognition to avoid cross fertilization. 8. Cleavage: a. )Sea Urchin: Microlecithal (little yolk) and therefore has holoblastic cleavage where cells divide completely. Completely hollow blastocoel Frog: Mesolecithal (moderate amount of yolk) but cleavage remains holoblastic where cells divide completely. Blastocoeal is half hollow Chick: Macrolecithal (large yolk) with meroblastic cleavage. Blastocoel is in blastoderm inside the egg yolk
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Cleavage at cytoplasm disk only Embryonic cell mass called blastoderm (not blastula) b.) Sea urchin: cleavage- holoblastic cell fate- blastopore- anus Frog: (vertebraes) Cleavage- holoblastic Cell fate- Blastopore- anus c.) size of zygote and a blastula 9. Gastrulation in a sea urchin: (known as morphogenesis) - cells move by changing shape and by changing cell-cell adhesion (stickiness) - creates the 3 germ layers and archenteron a.) 1. migration/ ingression of inner mesenchyme cells into blastocoel at vegetal pole 2. invagination - outer blastula cells move inward by changing shape at vegetal pole to form
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Bio II Unit I Study Guide - 6. Location in an organism...

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