the basic unit of life part 2 {module 4} Flashcards
har har freddy fazbear
() have cell walls
plants, bacteria, and fungi
The cell wall is a strong non-living layer around the outside of the cell membrane.
In plants specifically, the cell wall is made up of cellulose. Some cells also contain lignin in their cell walls. Lignin is waterproof and provides extra strength. The cell wall has three layers that aid in providing support. These layers are the ()
middle lamella, the primary cell wall, and the secondary cell wall
The cell wall gives the cell ()
shape, and support and also protects the cell.
All cells, both plant, animal and fungi, have a () The () surrounds the content of every cell, separating the inside of the cell from the outside. () have the same structure.
cell membrane
The cell membrane surrounds and protects the () and it is composed of a double layer (bilayer) of lipids and phospholipids.
cytoplasm
Phospholipids consist of a () head and a () tail.
water-loving (hydrophilic)
water-fearing (hydrophobic)
Many nutrients and gasses have to pass through the cell membrane from its environment, but not everything is good and healthy for the cell. The cell membrane is, therefore, () to ions and small molecules like hydrogen, sodium, oxygen, and carbon dioxide. Larger molecules like glucose and amino acids can also pass. The cell membrane controls the movement of substances in and out of the cell.
selectively permeable
yo! whats the function of cell membranes?
Osmosis, diffusion, and active transport of nutrients into the cell. The cell membrane also processes ingestion and secretion
structure:
Consists of two layers of phospholipids. Each phospholipid has a polar, hydrophilic (water-soluble) head as well as a non-polar, hydrophobic (water-insoluble) tail.
function:
It is a semi-permeable structure that does not allow materials to pass through the membrane freely, thus protecting the intra and extracellular environments of the cell.
name the component
Phospholipid bilayer
structure:
These are proteins found spanning the membrane from the inside of the cell (in the cytoplasm) to the outside of the cell. Membrane proteins have hydrophilic and hydrophobic regions that allow them to fit into the cell membrane
function:
Act as carrier proteins that control the movement of specific ions and molecules across the cell membrane.
name the component
Membrane proteins
structure:
Carbohydrate chains are attached to phospholipids on the outside surface of the membrane.
function:
Act as recognition sites for specific chemicals and are important in cell-to-cell attachment to form tissues.
name the component
Glycolipids
structure:
Consists of short carbohydrate chains attached to polypeptide chains and are found on the extracellular regions of the membrane.
function:
These proteins are useful for cell-to-cell recognition.
name the component
Glycoproteins
() is the spontaneous movement of molecules from a region of high concentration to a region of low concentration until the concentration of molecules is the same in both. It is said to occur down the concentration gradient
diffusion
() the movement of water from a region of high concentration or water potential to a region of low concentration or water potential through a semi-permeable membrane
Osmosis
he jelly-like substance that fills the inside of the cell, is known as the ()
cytoplasm
gimme the functions of a cytoplasm
The cytoplasm provides support to the cell by exerting pressure against the cell membrane. This helps the cell to keep its shape. This pressure is known as turgor pressure.
The cytoplasm is also where most of the cellular activities, like cell division, protein synthesis, and metabolism occur.
The cytoplasm is full of ribosomes and ribosomes help in the synthesis of protein.
It acts as a storage area for small lipids, proteins, and carbohydrates and the cytoplasm also suspends organelles and can transport them around the cell
define the nucleus
The nucleus is known as the control centre or the brain of the cell. It is usually found near the centre of an animal cell and on the side of a plant cell. It is also the largest organelle and contains all the genetic information of the cell (DNA). The presence of a nucleus is what distinguishes a eukaryotic cell from a prokaryotic cell.
the structure of a nucleus consists of ()
nuclear envelope, nuclear pores, nucleoplasm, nucleolus and dna
explain nuclear envelope
The nuclear membrane is a double-layer lipid membrane that is filled with special proteins that separate the nucleus and its contents from the cytoplasm.
explain nuclear pores
here are small little holes in the nuclear envelope called the nuclear pores and they help to regulate the exchange of materials such as RNA and proteins between the nucleus and the cytoplasm.
explain nucleolus
he nucleolus synthesises RNA and another type of nucleic acid.
explain chromatin
Long threads, called chromosomes are found inside the nucleoplasm. The chromosomes are folded tightly together, forming a network called the chromatin network. Chromatin is long, thin strands of DNA and Protein.
functions of a nucleus?
The cell nucleus has the very important function of controlling gene expression and ensuring that DNA replication takes place during the cell cycle.
The nucleus also controls the metabolic functions of the cell by producing mRNA (which encodes enzymes).
The nucleus transcribes DNA which encodes for structural proteins, like actin and keratin. This controls the structure of the cell.
The nucleus is also the site where ribosomes are made, called ribosomal RNA (rRNA). This is important for the construction of ribosomes. Ribosomes are where protein translation occurs, the process where proteins are made from amino acids.
The nucleus also contains genetic information (DNA) which transmits certain characteristics from parent to offspring.
gimme the main function of the mitochondria
The main function of the mitochondria is cellular respiration. During cellular respiration, oxygen is used to break down organic substances. The process releases energy which is used for different life functions in the cell
tell me about ribosomes
Ribosomes are found in the cytoplasm and are the sites where protein synthesis occurs. Ribosomes can be found in groups in the cytoplasm or occur singly, or they may be attached to the Endoplasmic reticulum - forming the rough endoplasmic reticulum
Ribosomes together with messenger RNA (mRNA) form a structure known as a polyribosome which is important in protein synthesis
tell me about the endoplasm reticulum
The Endoplasmic reticulum, or ER, is an organelle that consists of a double membrane made up of a network of hollow tubes, flattened sheets, and round sacs called cisternae. These folds form channels through the cell. The ER is found in eukaryotic cells and is located in the cytoplasm and connected to the nuclear envelope.
tell me about smooth endoplasm reticulum
The Smooth endoplasmic reticulum (sER) does not have any ribosomes attached to it. It manufactures lipids
be a lamb and tell me about The rough endoplasmic reticulum
The rough endoplasmic reticulum has ribosomes attached to it. It is responsible for the production of proteins and plays a role in membrane production. The folds in the membrane increase the surface area ensuring that more ribosomes can attach to it, allowing greater protein production.
define the golgi
Golgi bodies are found in most cells near the nucleus and the ER. They consist of a stack of membrane-bound organelles (imagine a stack of sandwiches) called cisternae. The Golgi body cisternae consist of enzymes that modify the packaged proteins (the products produced by the Golgi body). The membranes became pinched at the ends forming vesicles. These vesicles contain proteins and lipids.
The Golgi body receives and collects molecules (like proteins and lipids) from the ER, processes them, and packages them into vesicles. It, therefore, plays an important role in the transport of proteins and lipids. The Golgi body can be considered as the sorting organelle of the cell. It receives these molecules made by the ER and transfers them to where they are required. Think of the Golgi body as a “post office”.
define vacuoles
Vacuoles are found in the cytoplasm of most plant cells. They are very small or completely absent in animal cells. Plant cells generally will have one large vacuole that takes up most of the cell’s space. They are membrane-bound organelles, filled with fluid and covered by a selectively permeable membrane called the tonoplast. The fluid filling the vacuole consists of water, mineral salts, sugars, and amino acids
The main function of the vacuole is to digest and excrete cellular waste and store water and organic and inorganic substances.
The vacuole is responsible for maintaining the shape of the cell. When it is filled with water, it exerts pressure, pushing the cell membrane against the cell wall. This pressure is called turgor pressure
