Introduction to Cell Division Notes
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Transcript of Introduction to Cell Division Notes
Introduction to Cell Division
Notes
Cell Division
Where do new cells come from?
Other cells… skin cells make skin cells, muscle cells make muscle cells and so on.
A skin cell can not make a muscle cell, only another skin cell.
The process of one cell making another cell is called cell division.
Cell Division What is cell
division? how a cell
reproduces, makes a copy of itself.
how living things grow (Mitosis) and make sex cells (Meiosis).
Why do we need new cells? Need new cells to:
Grow Repair scratches and
tears (scars)
Prokaryotic vs. Eukaryotic??
• What is the difference?• Do both have a cell membrane?• YES!!!!
• Eukaryotic cells have a nucleus and organelles with membranes and Prokaryotic cells do NOT have a nucleus!!
Cell Division
Cell Divison for: 1. Prokaryotes (like
bacteria cells) Binary Fission (unicellular
organisms) DNA copied, cell grows, cell splits in two.
Unicellular organisms- this is how they reproduce.
Cell Division 2. Eukaryotes –
(plant/animal cells) Mitosis (multicellular
organisms) DNA copied, cell grows, cell splits in two.
new cells have identical genetic material; produces clones.
Mitosis is about the division of the nucleus.
Nucleus
Nucleus is important for: 1. Stores hereditary
information in its DNA. 2. DNA makes RNA 3. Contains the nucleolus
(where DNA is in nucleus, dark circle)
Nucleic Acids
Function of DNA – Store and transmit hereditary information DNA – stands for Deoxyribose Nucleic Acid
Cell Division: Mitosis
Before a cell can divide it must organize its DNA and form chromosomes, so it copies and divides DNA accurately.
Making Chromosomes
How DNA condenses to form chromosomes: 1.Strands of DNA wrap around proteins called
Histones. 2. This then forms a
molecule called chromatin. Chromatin is found in the
nucleus and is how DNA spends the majority of its life.
Chromosomes Chromatin continues to condense and
eventually it forms chromosomes. Chromosomes – tightly coiled packages of
DNA held together by proteins.
Chromosomes Chromatid – half of a
chromosome; forms as DNA copies itself before cell division
Centromere – holds the chromatids together until they separate
Chromosomes Each species has a unique number of chromosomes
How many chromosomes do humans have?
46 chromosomes or 23 pairs.
Chromosomes 2 Types of Chromosomes: 1. Sex Chromosomes – are the chromosomes
that determine the sex of an organism.
Female: XX
Male: XY
2. Autosomes – all other chromosomes Humans: 44 autosomal chromosomes
Chromosomes Karyotype – is a picture
of the chromosomes in a dividing cell.
22 homologous pairs of autosomes.
2 sex chromosomes
Chromosomes
Homologous chromosomes – two copies of each autosome (maternal and paternal)
Homologous chromosomes are the same size, shape, and carry genes for the same trait.
Chromosomes
Diploid Cells (2n)– are cells that have 46 chromosomes.
All cells in your body are diploid except sex cells
Haploid Cells (n)– cells that only have 23 chromosomes
Ex. Gametes (sex cells)
Chromosomes Examples of haploid
cells?
Gametes - sperm and egg cells; they have 23 chromosomes
Fertilization 23 in sperm + 23 in egg = 46