chapter 4 honors and lab biology. quick write : ◦ why do we need to learn about cells?
Post on 03-Jan-2016
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Cells were discovered due to microscopes in the early 17th century
ROBERT HOOKE 1665 (english scientist) examined a slice of cork, he saw “little boxes” they reminded him of small rooms….cells! These were dead plant cells.
ANTON VAN LEEUWENHOEK 1632-1723 (dutch microscope maker) first to observe living cells
Discovery of Cells….
Is the smallest unit of matter that can carry out all the processes of life.
Organelle: parts within a cell!
Cells
1. All living things are composed of one or more cells
2. Cells are the basic unity of structure and function in an organism
3. Cells come from the reproduction of existing cells.
Cell Theory(150 yrs. Passed after Hooke & Van Leeuwenhoek
Matthias Schleiden (1838) botanist, all plants are composed of cells
Theodor Schwann (1839) zoologist, all animals are composed of cells
Rudolf Virchow (1855) physician, cells come ONLY from other cells.
Three German Scientists early evidence for the cell theory…
Not all cells are alike! They vary in…◦ A) size◦ B) shape◦ C) internal organization
SIZE: range from .2m – 0.2um (most are 10-50um)-not all are microscopic (most are) ex: giraffe’s nerve cells extend 6.5 ft. down it’s leg!!
Cells are limited in size by the ratio between their outer surface area and their volume
Cell Diversity
Organelles: parts of a cell, have specific jobs
Tissues: groups of cells that have a similar function
Internal Organization
Organ SystemsOrgan systems- a group of organs that work together to perform a set of related tasks. Digestive system includes: the stomach, esophagus, intestines and mouth.
Cells→Tissues→Organs→Organ Systems
Cell Membrane – separates cell from external environment, gives shape and flexibility to cell, selectively permeable
Cell Organelles!
Cytoplasm: ◦ gelatin like aqueous fluid called cytosol◦ Cytoplasmic streaming◦ Mostly water but also salts and organic
molecules
Continue…
Mitochondia: power house of the cell! Where cellular respiration occurs, production of ATP, has it’s own DNA◦ Cristae: inner membrane creating many
folds to increase surface area
Continue…
Ribosomes: where proteins are made,◦ Free Floating Ribosome: make proteins for
the cell◦ Ribosomes attached to ER: make proteins
to be exported from the cell
Continue…
Endoplasmic Reticulum: (ER) acts as a highway for molecules to move around the cell.◦ Smooth ER: does NOT contain ribosomes◦ Rough ER: does contain ribosomes
Continue…
Golgi Apparatus (bodies) processes, packages, and secretes
a) product is assembled (moves from ER to golgi, where it is put together and adjusted)
b) product is packaged (in new sacs) c) product is mailed out (sent out of cell)
Continue…
Cilia: short hair like projections beat together to move an organism ex: humans trachea cilia move fluids and mucus! YUM
Continue….
Nucleus: brains! Control center of cell, DNA & RNA are made here!◦ Nuclear envolope: double membrane will pores◦ Chromatin: fine strands of DNA & protein◦ Nucleolus: inside nucleus where ribosomes are
made
Continue….
Lysosome: digestive enzymes, digest food, disease causing bacteria, old organelles, ex: lysosomes eat up tissue between fingers in embryos, usually only in animal cells
Continue…
Cytoskeleton- helps shape & support cells◦ Microtubules: long slender protein tubes
form spindle fibers during mitosis◦ Microfilaments: fine protein threads
Continue…
Cell Wall: rigid covering made of cellulose, protects cell, goes OUTSIDE cell membrane
Oranelles in Plant Cells ONLY
Plastids◦ a) chloroplasts : site for photosynthesis ◦ b) chromoplasts: stores red and yellow
pigment◦ c) leucoplasts: non pigmented
Continue….
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