BIO UNIT 4 CHAP 7.2 Chromosomes

Chromosome structure

- tightly condensed

- compact structure

- often x shaped- tightly condensed

chromosome function

- protects DNA

- allows for DNA to be separated into daughter cells

Chromatin structure

Unwond, spread out fibers

Chromatin Function

regulated gene expression, transcription and DNA replication

two forms of chromatin

heterochromatin euchromatin

Heterochromatin Def

tightly coiled (condensed) complex of proteins and DNA

few genes and limited transcription activity

Euchromatin Def

loosley coiled complex of protiens and DNA

many genes and high transcription activity

Histone

a protein that spools DNA in eukaryotic cells

when a cell begins to divide (cell division)

both forms of chromatin condense by coiling tighly around histone proteins

eventually becomes thick enough to see under a microscope

chromosome types

single, duplicated

Duplicated chromosomes

have undergone replication in rediness for cell division

duplicated chromosome structure

x shaped

2 sister chromatids joined by a centromere

diploid cells

two copies of each chromosome

haploid cells

one copy of each chromosome

sister chromatids

two identical copies of a single chromosome

formed by replicated and connected by a centromere

centromere

region of a chromosome that links two sister chromatids

chromatid

one of two identical halves of a replicated chromosome

unduplicated chromosome

A single, complete chromosome that hasn't yet undergone replication

homologous pair

set of two matching chromosomes in a cell

one inherited from each biological parent

carries the same genes in the same order, same size, same centromere location

similar (not identical) dna sequence

alleles

a specific or alternate variation of a gene