BIOSC-139 Lecture Notes - Lecture 16: Nuclear Lamina, Meiosis, Semiconservative Replication
26 Aug 2020
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Document Summary
Cellular extensions: microvilli, minute, fingerlike extensions of plasma membrane, increase surface area for absorption, core of actin filaments for stiffening. Nucleoli: dark-staining spherical bodies within nucleus, involved in rrna synthesis and ribosome subunit assembly, associated with nucleolar organizer regions, contains dna coding for rrna, usually one or two per cell. Chromatin: threadlike strands of dna (30%), histone proteins (60%), and rna (10%, arranged in fundamental units called nucleosomes, histones pack long dna molecules; involved in gene regulation, condense into bar-like bodies called chromosomes when cell starts to divide. Cell cycle: defines changes from formation of cell until it reproduces, includes, interphase, cell grows and carries out functions, cell division (mitotic phase, divides into two cells. Interphase: period from cell formation to cell division, nuclear material called chromatin, three subphases, g1 (gap 1) vigorous growth and metabolism. Cells that permanently cease dividing said to be in g0 phase: s (synthetic) dna replication occurs, g2 (gap 2) preparation for division.
