Transcript Cells and More Cells

Cells and More Cells
Homework Questions
Page 14 #1,3
Page 15 #2,3,4,5
Page 18 #1-3
Page 22 #6,7
Page 26 #9,10
Page 28 #1,3,8
Page 32 #2,3
Cells and Cell Structure
 Cells  The smallest unit that can perform the functions of life; there are
many different types of cells even within the same organism
 Cells are made up of organelles; specialized structures that perform
specific functions within the cell
 The first organelle discovered within the cell was the nucleus which is
the structure responsible for controlling the overall activity of the cell
 The nucleus of the cell is made up of a nuclear membrane which protects
the contents of the nucleus, a nucleolus which makes ribosomes which in
turn synthesize proteins and nuclear pores which allow materials in and
out of the nucleus
Cells and Cell Structure
 The fluid material between the cell membrane and the nucleus is known as
the cytosol which is filled with many specialized organelles
 The organelles of the cell each play a role in the proper functioning of cell;
a critical role of many organelles includes the production, storage or
transport of proteins
 Proteins are essential for growth and repair of body tissues; all cells
depend on proteins to carry out the life processes that keep you healthy
 The cytosol and organelles it contains is collectively called Cytoplasm
Animal Cell
Plant Cell
The Cell Theory
All living organisms are made of one or more cells
2. The cell is the basic organizational unit of life
3. All cells come from pre-existing cells
1.
Cells and Cell Structure
 Some types of organelles are found in both plant and animal cells, while
other types are found only in one or the other
 E.g. Mitochondria are found in both plant and animal cells while chloroplasts
are found only in plant cells, not in animal cell
 Cellular Respiration is the process by which cells produce energy using glucose;
this process occurs in the mitochondria of cells
 Refer to Figure 1.5 and 1.6 on page 12 of your text  YOU ARE
RESPONSIBLE TO KNOW THE NAME AND FUNCTION OF EACH TYPE OF
ORGANELLE FOUND IN BOTH AN ANIMAL AND PLANT CELL!
Genes
 The nucleus of the cell contains the master set of instructions that
determines what each cell will become, how it will function and
how long it will live  These instructions are carried by threadlike structures in the nucleus known as Chromosomes
 Every plant and animal species has a specific number of
chromosomes in the nucleus of each cell  these chromosomes
come in pairs; one from each parent when an egg and a sperm
unite to form a fertilized egg
 E.g. Humans have 46 chromosomes (23 donated from the mother’s egg and 23
donated from the father’s sperm)
Genes
 Chromosomes are made of a material known as deoxyribonucleic acid
(DNA) which contains all of a cells genetic information
 Each chromosome consists of a single molecule of DNA, which is
divided into segments called genes
 Genes are located in specific places on the chromosome and the provide
the necessary instructions for creating proteins
 Refer to Figure 1.9 on page 17
 You are responsible for knowing how the 4 types of molecules; Adenine
(A), Guanine (G), Cytosine (C) and Thymine (T) form the building
blocks of DNA and how the order in which these building blocks are
strung together form the genetic code
• Each DNA molecule
contains hundreds of
thousands of genes
• Genes determine what
kinds of proteins your
cells can make and in
turn how your body
looks and functions
• Each type of protein a
cell creates is designed
to do a specific job in
your body
Mutations
 The specific proteins that genes code for depend on the order of the
DNA building blocks in the gene
 A change in the given order of the A,C,T,G building blocks in a
segment of DNA is known as a mutation
 A mutation in a gene can alter the structure and function of the
proteins it produces
 E.g. Individuals with sickle cell anemia have a mutation in the gene that codes
for a protein in red blood cells called hemoglobin  this inhibits the ability of
red blood cells to carry oxygen to the bodies different organ systems
Mutations
 Mutations can be random,
uncontrolled events or they can be
caused by mutagens  substances or
factors that can cause a mutation in
DNA by physically damaging DNA
 Some examples of mutagens are
electromagnetic radiation (X rays and
UV rays from the sun), chemicals
such as mercury and tar from
cigarettes
 Not all mutations are harmful 
some mutations can occur in portions
of DNA that do not code for proteins
(mutations in non-genetic parts of a
DNA molecule)
Cell Reproduction
 Cell reproduction is the process by which new
cells are formed from existing cells
 In cell reproduction, there is only one parent
cell; the parent cell divides to produce two new
cells which are called daughter cells  The
two daughter cells are identical to each other
and to their parent cell
 NOTE: Cell reproduction is different than
sexual reproduction where two parents mate and
the offspring receives half of the genes from each
parent (one chromosome from each parent)
Cell Division
 Cell Division is the process by which a parent cell divides into two
daughter cells
 For single-celled organisms, cell division is the main process by
which individuals reproduce and increase a population size
 For multi-cellular organisms, cell division is the process by which a
fertilized egg (a single cell) becomes an adult with millions of cells
 It is also the process where lost or damaged cells are replaced
Cell Division
 A cell cannot simply split down the middle to divide  It has a
specialized multi-step division process which includes;
 Mitosis  The process by which a parent cells nucleus duplicates and
divides into 2 equal parts
 Mitosis is broken down into 4 distinct phases
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
 Cytokinesis  Following mitosis, the process by which the two
nuclei and the cell contents separate into two daughter cells