IB Bio HL Unit 8

DNA packaging

condensing DNA in order to fit all the DNA for a cell in the nucleus

nucleosome

a stretch of DNA wrapped around a core of 8 histone proteins, with a 9th histone protein holding DNA around a nucleosome

DNA packaging

condensing DNA in order to fit all the DNA for a cell in the nucleus

nucleosome

a stretch of DNA wrapped around a core of 8 histone proteins, with a 9th histone protein holding DNA around a nucleosome

linker DNA

a stretch of non-wrapped DNA, holds nucleosomes together and connect to neighboring histones

chromatin

loosely packaged DNA found in non-dividing cells

chromasomes

condensed chromatin found in dividing cells

chromatids

2 DNA molecules after DNA replication, tethered at centromere

duplicated chromosome

x-shaped package of chromosomes

centromere

center of duplicated chromosome that sister chromatids attach to

sister chromatids

connected chromosomes at the centromere

gene expression and DNA packaging

chromosomes make DNA inaccessible, so no gene expression

controlling gene expression by DNA packaging

manipulation of levels of DNA packaging, looser packaging allows for more gene expression

cell division

asexual reproduction in unicellular organisms that allows for cells to be genetically identical

cell proliferation: growth

a function of cell proliferation that increases size and complexity of multicellular organisms by producing more cells

cell proliferation: cell replacement

tissues require routine replacement, helps maintain healthy tissues and replaces dead cells

cell proliferation: tissue repair

wound healing requires cells to proliferate to heal damaged tissues.

cell cycle

sequence of events a cell undergoes, including growth, DNA replication, nuclear and cytoplasmic division

Gap 1 (G₁)

first part of interphase, cell doubles in size, binary fission and protein synthesis occur.

synthesis (interphase)

2nd phase of interphase, DNA replicates in nucleus

Gap 2 (G₂)

continued growth of microtubules necessary for cell division

mitosis

first part of mitotic phase, division of nucleus

cytokinesis

2nd part of mitotic phase, division of cytoplasm

DNA found in interphase

chromatin

DNA found in mitotic phase

chromosomes