Transcript sister chromatids

Cell Reproduction Introduction
Cell reproduction is different for
prokaryotes than eukaryotes. Why?
What do you know about the two
different types of cells?
Chromosome Terminology
• Chromatin: tangled mass of threadlike DNA in
nondividing cell
• Chromosomes: condensed rod-shaped DNA
molecules formed during division
• Sister chromatids: 2 exact copies of genetic
information that make up each chromosome
• Centomere: location where sister chromatids
are attached together
• Genes: segment of DNA that CODES FOR A
PROTIEN
• Each duplicated chromosome consists of two
sister chromatids which contain identical copies
of the chromosome’s DNA.
• As they condense, the
region where the strands
connect shrinks to a
narrow area, is the
centromere.
• Later, the sister
chromatids are pulled
apart and repackaged
into two new nuclei at
opposite ends of
Fig. 12.3
the parent cell.
Prokaryotic Cell Reproduction
Binary fission
• Asexual reproduction
• Offspring are identical
• 2 stages:
1) DNA is copied
2) Cell divides
a) New cell membrane formed between 2 copies of DNA
b) Squeezes together and eventually pinches off to 2 cells
Eukaryotic Cell Reproduction
•Two types of Cell Reproduction For Eukaryotes
–Cell Division/Reproduction involving Mitosis
–Cell Division/Reproduction involving Meiosis
• Mitotic Reproduction:
Asexual; produces 2 identical daughter cells
from original mother cell.
• Meiotic Reproduction:
Produces 4 non-identical “gametes” from one
mother cell; reduces the number of
chromosomes in the cell by ½; leads to
sexual reproduction
Chromosome Number Terminology
• Diploid number (2N) : characteristic
chromosome number in common somatic
eukaryotic cells
chromosomes exist in pairs due to presence
of two complete sets of chromosomes
one maternal set
one paternal set
Chromosome Number Terminology
• Haploid number (N): half the diploid
number; only one set of mixed maternal
and paternal chromosomes;
found only in gametes (Technically, all
prokaryotes are haploid)
Cell Type Terminology
• Somatic Cells: All non-sex cells; normal
body cells (skin, muscle, liver, root, leaf,
stem, etc.)
–Theoretically always Diploid
• Gametes (germ cells): Sex cells –sperm,
egg (ovum), sexual spores
–Theoretically always Haploid
Let’s Practice!
Get out your packets and turn
to page 19.