sci wa

• The cell cycle describes the sequence of cell growth and division
• a cell spend most of its life in a stage called interphase
• interphase has 3 stages followed by cell division
• G1 of interphase is the growth phase of the cycle
• S stage of interphase is when a copy of dna is being made
• a cell undergoes mitosis to form 2 new nuclei
• mitosis divides to form 2 individual cells during cytokinesis
• prophase of mitosis is when we first see the chromosome structure and microtubules appear from the centrosome
• prometaphase of mitosis is when the nuclear membrane breaks down and microtubule strands attach to the kinetochore
• metaphase of mitosis is when chromatids align along the center facing opposite poles of the cell
• anaphase of mitosis is when a shortening of microtubules occur attached to the kinetochore occurs and poles of the cell move appart causing separation of sister chromatids
• telophase of mitosis is when the nuclear membrane reforms and chromosomes uncoil and return to an uncondensed state
• eukaryotic somatic cells undergo mitosis
• reproduction is the production of an offspring
• asexual reproduction is generating a new individual without the fusion of sperm and egg cells
• binary fission is when 2 new genetically identical cells are produced. examples are sea anemones and bacteria.
• budding results from the outgrowth of a cell due to cell division leading to separation into 2 individuals. examples are corals and invertebrates
• fragmentation and regeneration are 2 different processes yet go hand in hand. fragmentation is breaking of the body into several pieces white regeneration is regrowth of lost body parts. examples are tapeworm and rugworm
• parthenogenesis is when an egg develops without fertilization. examples are bees, ants, and sharks
• father depends gender
• females have XX chromosomes while males have XY chromosomes
• sexual reproduction involves the fusion of haploid gametes, forming a diploid cell and eventually a new individual
• haploids from each parent results into a diploid cell
• an egg is released from the ovary during ovulation, the most fertile phase
• the egg travels through the fallopian tube, where it can meet the sperm cell
• the sperm, deposited into the vagina during sexual intercourse, swim through the cervix and enters the uterus
• if a sperm successfully penetrates the egg, fertilization occurs forming a zygote
• in early pregnancy, zygote to blastocyst occurs when the zygote undergoes several cell division forming a blastocyst
• implantation is when the blastocyst implants the lining of the uterus, starting the early stage of pregnancy
• embryo formation is when the cells differentiate into embryonic tissues, and the embryo begins to form
• meiosis is the type of cell division that produces gametes such a sperm and egg cells. it is broken down into 2 stages
• prohase 1 of meiosis 1 starts with a diploid cell
• prohase 1 of meiosis 1 is when after the DNA in teh chromatin replicates, it condenses into chromosomes
• synapsis is when each chromosome pairs and binds with its homologous chromosome
• different versions of the same genes are called alleles
• crossing over is when chromatids from each homologous chromosome exchange segments of alleles
• crossing over results in genetic variety of offspring
• at the end of prophase 1 of meiosis 1, the nuclear membrane then breaks down, then the centrosomes move to opposite ends of the cell and spindle fibers form
• metaphase 1 of meiosis 1 is when chromosomes are aligned at the equator of the cell and spindle fibers attach to the centromere of each chromosome
• anaphase 1 of meiosis 1 is when homologous chromosomes are pulled to the opposite ends of the cell and sister chromatids remain attached