Unit 3 Cells Flashcards
Heterotrophs
They are consumers. They CANNOT make their own food. They get food by consuming other living organisms.
Autotrophs
They are producers. They CAN make their own food and are not dependent on outside sources for their food.
Robert Hooke
He looked at thin slicers of cork (planet cells) under the microscope. Cork seemed to be made of thousands of thin, empty chambers. Hooke called these chambers “cells” because they reminded him of the tiny rooms in which he lived in the monastery.
Cell membrane
It is also known as the plasma membrane. It separates the internal chemical reactions of the cell from the external environment. it regulates the passage of materials into and out of the cell by allowing only certain molecules to enter and leave.
Nucleus
It is the control center of the cell. It is filled with nucleoplasm. It contains nearly all of the cell’s DNA. It is surrounded by a nuclear membrane. It is a site where DNA is transcribed into RNA. It is the carrier of genetic information. It controls the reproduction of the cell, activities, and directs a proteins synthesis by sending messages out to the ribosomes.
Chromatin
When the cell is not dividing, the DNA is in the form of a threadlike material
Chromosome
When the cell is actively dividing, the chromatin condenses.
Nucleolus
It manufactures the subunits that make up ribosomes. The 2 subunits are large and small. The subunits pass through the pores of the nucleus to the cytoplasm where they combine to form ribosomes.
Ribosomes
They may be found free floating in the cytoplasm, or they may be found attached to the rough E.R. They are composed of protein and RNA and are not membrane-bound organelles. They are the site of protein synthesis. All proteins of the cell are made by this.
Endoplasmic Reticulum (E.R)
The internal membrane system of a cell. This system of membranes is so extensive throughout the cell that it accounts for more than half the total membrane in a cell. It functions as an “intracellular highway” that provides a path along which molecules move from one part of the cell to another.
Rough E.R
It is covered with attached ribosomes. It is involved in the making of proteins. Newly made proteins leave the ribosomes and are inserted into spaces where they are modified and shaped into functioning proteins.
Smooth E.R
It has no ribosomes. the function of the it is to make lipids that will be used in membranes
Golgi Apparatus (complex)
Proteins that are produced in the rough E.R are transported to this organelle. It appears as a stack of loosely connected membranes. The function of the Golgi is to modify, sort and package the proteins that have arrived from the E.R. These proteins with either be stored in the cell or be secreted to the outside of the cell.
Vesicles
They are small, spherical sacs that are surrounded by a single membrane. They are classified according to their contents. Types of them include transport vesicles, lysosomes, and peroxisomes.
Protein Synthesis and Transport
1) Proteins are assembled by ribosomes on the rough E.R
2) Vesicles transport proteins to the Golgi complex
3) The Golgi complex completes the modifications on proteins.
4) Functional proteins are packaged in vesicles and leave the Golgi complex
5) Vesicles fuse with the cell membrane to release the newly formed proteins to the outside of the cell
6) Vesicles containing enzymes remain inside the cell as lysosomes
