Cells. The basic units of a living system or organism

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1 Cells The basic units of a living system or organism

2 Cell Theory developed by 3 German scientists: Matthias Schleiden, Theodor Schwann, and Rudolf Virchow

3 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.

4 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.

5 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

6 Prokaryote Eukaryote

7 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 ORGANISM (BODY) ORGAN SYSTEM ORGANS TISSUES CELLS

8 Representative Animal Cell

9 Animal Cell

10 Representative Plant Cell

11 Plant Cell

12 Organelles -Tiny cell structures that are specialized parts of a cell that have specific functions a cell organ.

13 CELL MEMBRANE gate keeper outer boundary (or layer) of the cell controls the movement of materials into and out of the cell

14 CELL WALL found in plant cells tough rigid boundary made of cellulose gives cells their shape (it also provides protection, as well as support)

15 CYTOPLASM cell fluid a gel-like material inside the cell Many cellular activities occur here and where the organelles are contained

16 NUCLEUS brain of the cell controls cell processes Contains DNA or chromosomes - the heredity material or genetic blueprint of the cell

17 DNA Hereditary material Chromosomes DNA Protiens Form for cell division Chromatin

18 NUCLEAR MEMBRANE materials pass in and out through tiny holes called porins

19 Nucleolus Most cells have 2 or more Directs synthesis of RNA Forms ribosomes

20 CHLOROPLASTS energy processing organelles found only in plant cells place where food is made for plant cells

21 MITOCHONDRIA powerhouse converts food (glucose) to energy (ATP)

22 RIBOSOMES protein factories place where protein is made in the cells some are attached some float in the cytoplasm

23 ENDOPLASMIC RETICULUM conveyer belt transports synthesized proteins throughout the cell

24 GOLGI BODIES (Apparatus) sort, modify, process, and ship the proteins through the cell (Also known As GOLGI Apparatus)

25 VACUOLES storage store water, sugar, salts, nutrients, & wastes in cells maintains the proper pressure to provide structure and support in plant cells

26 LYSOSOMES contain chemicals that break down waste materials.

27 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

28 What is a unicellular organism? Any life form that consists of a single cell. They can move, digest food, and reproduce.

29 Euglena 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.

30 Euglena Unicellular, eukaryotic, both Heterotrophic and autotrophic Moves- Flagella Reproduces- fission (cell splits) Eats- eyespot senses light to gather for photosynthesis

31 Euglena

32 Amoeba 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.

33 Amoebas Unicellular, Eukaryotic, heterotrophic Moves-using Psuedopods Reproduces- Binary fission Eats-engulfing

34 Amoeba

35 Volvox 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.

36 Volvox Unicellular, eukaryotic, autotrophic Moves- flagella Reproduces- both sexually and asexually Eats- by using the eye spot to sense light so photosynthesis can occur.

37 Volvox

38 Paramecium 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.

39 Paramecium Unicellular, eukaryotic, heterotrophic Moves- cilia Reproduces-sexually and asexually Eats food from environment- through oral grove, food vacuole, and anal pore.

40 Paramecium

41 Many organisms, especially unicellular organisms, reproduce by means of cell division called asexual reproduc/on Ex: bacteria

Living things grow by producing more cells, NOT because each cell increases in

42 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

43 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 2 Daughter Cells Parent Cell

44 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

45 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

46 ChromaHn to chromosomes illustrahon: ChromaHn Duplicates itself Coils up into chromosomes Why does DNA need to change from chromahn to chromosome? More efficient division

soma/c (body) cells Why does mitosis occur?

47 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

48 4 phases of nuclear division (mitosis), directed by the cell s DNA (PMAT) Prophase Metaphase (Middle) Anaphase (Apart) Anaphase (Apart) Telophase (Two)

49 Phase Interphase Prophase Metaphase Anaphase Telophase Cytokinesis Chromosome Appearance & Loca/on DNA copies itself; chromatin Chromosomes coil up Chromosomes line up in the middle Chromosome copies divide and move apart Chromosomes uncoil back into chromatin Chromati n Important Events DNA replication, cell grows and replicates organelles Nuclear envelope disappears, spindle fibers form Spindle fibers connect to chromosomes Spindle fibers pull chromosome copies apart to opposite poles Nuclear envelopes reform, 2 new nuclei are formed, spindle fibers disappear Division of the rest of the cell: cytoplasm and organelles

SEXUAL REPRODUCTION Sex cells formed by meiosis Requires 2 parents Offspring not identical Meiosis The process that results in the formation of

50 SEXUAL REPRODUCTION Sex cells formed by meiosis Requires 2 parents Offspring not identical Meiosis The process that results in the formation of gametes Gametes Sex cells, egg or sperm, which have haploid chromosomes Haploid Haploid means HALF, as in the number of chromosomes, written as n

51 Fertilization The union of an egg and a sperm n Zygote n 2n The cell that is formed when the egg becomes fertilized by the sperm. This results in a full set of chromosomes. Diploid Diploid means they have chromosome found in pairs, written as 2n

52 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.

53 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.

7 th Grade Science Unit 2NCFE Review

7 th Grade Science Unit 2NCFE Review Cells The basic units of a living system or organism 2 Types of Cells: Prokaryotic - Cells that don t have a membrane-covered nucleus for example: bacteria Eukaryotic