The basic units of a living system or...
Transcript of The basic units of a living system or...
Cells
• The basic units of a living system or organism
Cell Theory –
• developed by 3 German scientists:
• Matthias Schleiden, • Theodor Schwann, • and Rudolf Virchow
These scientists discoveries led to the cell theory…
What is the CELL THEORY??? Theory that states… 1. All organisms are made of one or
more cells. 2. The cell is the basic unit of life
which can perform life processes. 3. All cells come from other living
cells.
How do we know cells exist?
• Invention of the microscope made it possible for people to discover and learn about cells
• Robert Hooke looked at cork cells
• Anton van Leuenhock used a simple microscope and was the first person to see microorganisms.
2 Types of Cells:
• Prokaryotic - Cells that don’t have a membrane-covered nucleus for example: bacteria
• Eukaryotic – Cells with a nucleus covered by a membrane for example: plant and animal cells
Prokaryote Eukaryote
How are cells organized?
Ø Complex living things are organized into 5 levels. Ø Cells carry on the processes that keep us alive. Examples:
Red Blood Cells Muscle Cells Skin Cells CELLS
TISSUES
ORGANS
ORGAN SYSTEM
ORGANISM (BODY)
Representative Animal Cell
Animal Cell
Representative Plant Cell
Plant Cell
Organelles
• -Tiny cell structures that are specialized parts of a cell that have specific functions – a cell “organ.”
CELL MEMBRANE
• – “gate keeper” • outer boundary (or layer) of
the cell • controls the movement of
materials into and out of the cell
CELL WALL
• found in plant cells • tough rigid boundary – made
of cellulose • gives cells their shape (it also
provides protection, as well as support)
CYTOPLASM
• – “cell fluid” • a gel-like material inside the
cell • Many cellular activities occur
here and where the organelles are contained
NUCLEUS
– “brain of the cell” • controls cell processes • Contains DNA or chromosomes
- the heredity material or genetic blueprint of the cell
DNA
• Hereditary material
• Chromosomes – DNA – Protiens – Form for cell division
• Chromatin
NUCLEAR MEMBRANE
• – materials pass in and out through tiny holes called porins
Nucleolus
• Most cells have 2 or more • Directs synthesis of RNA • Forms ribosomes
CHLOROPLASTS
• – “energy processing organelles” • found only in plant cells • place where food is made for
plant cells
MITOCHONDRIA
• – “powerhouse” • converts food (glucose) to
energy (ATP)
RIBOSOMES
• – “protein factories” • place where protein is made in
the cells • some are attached – some float in the cytoplasm
ENDOPLASMIC RETICULUM
• – “conveyer belt” • transports synthesized proteins
throughout the cell
GOLGI BODIES (Apparatus)
• sort, modify, process, and ship the proteins through the cell
• (Also known As GOLGI Apparatus)
VACUOLES • – “storage” • store water, sugar, salts,
nutrients, & wastes in cells • maintains the proper pressure
to provide structure and support in plant cells
LYSOSOMES
• contain chemicals that break down waste materials.
Unicellular organisms
• Some organisms only consist of a single cell
• But these do usually have the components of cells (nucleus, membrane etc)
Image Credit Paramecium
• Any life form that consists of a single cell.
• They can move, digest food, and reproduce.
What is a unicellular organism?
• Environment: Ponds or puddles with rich organic matter.
• Movement: By flagella • Important Structures:
– Cell Membrane – Nucleus: controls cell activities and contains DNA – Flagellum: helps to move – Chloroplast: helps with photosynthesis – Contractile Vacuole: removes excess water – Cytoplasm
• Food: They make their own food or absorb food from their environment.
Euglena
Euglena
• Unicellular, eukaryotic, both Heterotrophic and autotrophic
• Moves- Flagella • Reproduces- fission (cell splits) • Eats- eyespot senses light to gather for
photosynthesis
Euglena
• Environment: Mud at the bottom of freshwater ponds. • Movement: They change shapes which allows them to
move with their psuedopods. • Important Structures:
– Cytoplasm: carries out chemical reactions – Nucleus: controls the cell – Cell Membrane: allows substances to enter and exit the
cell – Food Vacuole: digests food – Contractile Vacuole: gets rid of excess water – Pseudopodium: what allows it to move over mud (false
foot) • Capturing Prey: They surround their prey and engulf it.
Amoeba
Amoebas
• Unicellular, Eukaryotic, heterotrophic • Moves-using Psuedopods • Reproduces- Binary fission • Eats-engulfing
Amoeba
• Environment: ponds, ditches, shallow puddles
• Movement: They beat cillia which allows it to swim.
• Important Structures: – Daughter colonies – Cillia: helps to move – Chloroplast: contains chlorophyll
• Food: makes its own food by photosynthesis.
Volvox
Volvox
• Unicellular, eukaryotic, autotrophic • Moves- flagella • Reproduces- both sexually and asexually • Eats- by using the eye spot to sense light
so photosynthesis can occur.
Volvox
• Environment: Fresh water or stagnant water • Movement: Cilia bend and straighten helping
propel the paramecium through water • Important Structures:
– Contractile Vacuoles (2): removes excess water – Cytoplasm: water absorption – Cilia: hair-like projections that propel it through
water – Nucleus: controls cell activities
• Food: uses cilia to sweep the food into the cell.
Paramecium
Paramecium
• Unicellular, eukaryotic, heterotrophic • Moves- cilia • Reproduces-sexually and asexually • Eats food from environment- through oral
grove, food vacuole, and anal pore.
Paramecium
• Many organisms, especially unicellular organisms, reproduce by means of cell division – called asexual reproduc/on – Ex: bacteria
Cell Division—Mitosis Notes Cell Division — process by which a cell divides into 2 new cells • Why do cells need to divide? 1. Living things grow by producing more cells, NOT because each cell increases in size
2. Repair of damaged Hssue 3. If cell gets too big, it cannot get enough nutrients into the cell and wastes out of the cell
• The original cell is called the parent cell; 2 new cells are called daughter cells
• Before cell division occurs , the cell replicates (copies) all of its DNA, so each daughter cell gets complete set of gene/c informa/on from parent cell
• Each daughter cell is exactly like the parent cell – same kind and number of chromosomes as the original cell
Parent Cell
2 Daughter
Cells
DNA • DNA is located in the nucleus and controls all cell ac/vi/es including cell division
• Long and thread-‐like DNA in a non-‐dividing cell is called chroma/n
• Doubled, coiled, short DNA in a dividing cell is called chromosome Consists of 2 parts: chroma/d and centromere
o 2 idenHcal “sister” chromaHds aVached at an area in the middle called a centromere
o When cells divide, “sister” chroma/ds separate and 1 goes to each new cell
ChromaHn
Duplicates itself
Coils up into chromosomes
• ChromaHn to chromosomes illustraHon:
Why does DNA need to change from chromaHn to chromosome? More efficient division
Mitosis – division of the nucleus into 2 nuclei, each with the same number of chromosomes • Mitosis occurs in all the soma/c (body) cells Why does mitosis occur? So each new daughter cell has nucleus with a complete
set of chromosomes
Anaphase—(Apart)
Prophase Metaphase—(Middle)
Telophase—(Two) Anaphase—(Apart)
• 4 phases of nuclear division (mitosis), directed by the cell’s DNA (PMAT)
Phase Chromosome Appearance & Loca/on Important Events
Interphase
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
DNA replication, cell grows and replicates organelles Nuclear envelope disappears, spindle fibers form
DNA copies itself; chromatin
Chromosomes coil up
Chromosomes line up in the middle
Spindle fibers connect to chromosomes
Chromosome copies divide and move apart
Spindle fibers pull chromosome copies apart to opposite poles
Chromosomes uncoil back into chromatin
Nuclear envelopes reform, 2 new nuclei are formed, spindle fibers disappear Division of the rest of the cell: cytoplasm and organelles
Chromatin
SEXUAL REPRODUCTION
Sex cells formed by meiosis Requires 2 parents
Offspring not identical
The process that results in the formation of gametes
Sex cells, egg or sperm, which have haploid chromosomes
Haploid means HALF, as in the number of chromosomes, written as n
Meiosis
Gametes
Haploid
Fertilization
The union of an egg and a sperm
The cell that is formed when the egg becomes fertilized by the sperm. This results in a full set of chromosomes.
Diploid means they have chromosome found in pairs, written as 2n
n
n 2n Zygote
Diploid
Homologous Chromosomes
Similar chromosomes that are found in pairs. The paired chromosomes come from the mother and father.
* Human body cells have 46 chromosomes each * Human body cells have 23 homologous pairs
Meiosis and Fertilization
Important for survival of many species, because these processes result in genetic variation of offspring.
A kind of cell division that results in gametes (sex cells) with half the number of chromosomes.
Meiosis Overview
• Human body cells have 46 chromosomes.
• Each parent contributes 23 chromosomes.
• Takes place in sex cells (gametes): egg and sperm
• Delete the next line.