Botany Lec 4 Which of the following molecules binds both a nucleic acid and to an amino acid during protein synthesis? Answer: tRNA Which of the following proteins would reach its operational cellular location via posttranslational import? Answer: a protein that functions within a nucleus Explanation: Protein has to get where it is going (cytosol- pro-translational- endomembrane system or posttranslational- free ribosome; stay outside of endomembrane system) Review session Fri Oct 16th Two types of Cell Division: Mitosis (duplication division 2n-2n or n-n and Meiosis (reduction division 2n-n) Mitosis: cells are genetically identical, occur inmost cells and in diff. parts of a plant?s lifecycle Meiosis: cells are unique, occurs in sex cells Cytokineses- growth and repair Apical Meristems of Root & Shoot places where plant grows up and down Mitosis- (looking at one chromosome) Cell cycle- goes through s face- DNA is replicated (made up of two sister chromatids that are identical) and separated into two separate nuclei (contain identical genetic material) Early prophase- 4 chromosomes in the cell (2n=4) strands of chromatin, start to condense (already been through S face- replication has already occurred), at late prophase we can see they are fully condensed (x shape), metaphase- line up at the equator of the nucleus (have sister chromatids), anaphase- cytoskeleton then pulls apart chromosomes, when separated= daughter chromosomes Separation of sister chromatids= Mitosis Pre-prophase band- predicts the future plane of cell division (later on where cell will divide), breaks down gets rebuilt up in mitotic spindle (getting ready to pull apart sister chromatids), mitotic spindle breaks down and forms phragmoplast (helps direct vesicles that are being sent out to the gogli- directs towards region where cell plate is being formed; contain cell material to build cell wall; continues in cytokinesis) Phragmosome- The phragmosome divides the vacuole. Nucleus moves to center of the vacuole along cytoplasmic strands; as it advances across the cell the nucleus divides; phragmoplast forms (directing vesicles) Made up of cytoplasm and cytoskeleton components that divides the vacuole (in cells that have large vacuoles that are going through mitosis) Phragmoplast- Cytoskeletal structure, has a different function Directs vesicles to the growing cell plate Diploid- pairs of chromosomes Meiosis, Heredity and Mendelian Genetics Meiosis- physical bases of heredity Sexual reproduction Haploid(n) spores (that eventually give rise to gametes) (step 2) Fertilization= diploid (2n) zygote- restores diploid (haploid+ haploid) Two diploid parents produce diploid offspring- has to be reduction! (if not we would end up with 4n cell- if 2n +2n came together) Only happening in special reproductive cells Gametes- sperm and egg; come together through fertilization; form diploid zygote; goes through cell cycle (DNA replication, divides by mitosis) Meiosis produces haploid cells from a diploid cell, chromosome are unreplicated- become replicated, meiosis involves two nuclear divisions (meiosis 1- separate homologous chromosomes and meiosis II- sister chromatids) Homologous chromosomes- not identical ? pair of chromosome- same genes, but may have different alleles Alleles, Genes and Loci- looking at-homologous pair of unreplicated chromosome Locus- gene location On locus there is a gene for flower color Not all plants have same alleles- different forms of the same genes ex. Purple and white Figure 8-5 Early prophase- Chromosomes are condensing
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