Cell structure and organisation

Characteristics of a prokaryotic cell

-circular DNA

-70S ribosomes

-mesosomes

What is the function of a plasma membrane

Selectively permeable barrier between internal and external environments of a cell

What is the structure of the plasma membrane

Phospholipid bilayer with proteins embedded in the bilayer

Carbohydrates on extra cellular surface

What is the structure of mesosome

Infolding of the plasma membrane

What is the function of mesosome

Increase surface area of membrane

Higher rate of absorption of nutrients/excretion of waste

What is the function of smooth endoplasmic reticulum

Involved in the synthesis and transport of lipids

Characteristics of a Eukaryotic cell

-DNA contained in nuclear membrane

-membrane bound organelles

-80S ribosomes

What is the structure of Nucleoids and Plasmids

Circular DNA molecules free in cytoplasm

Function of Nucleoids and plasmids

Nucleoid- carries bacterial genetic code. The main DNA molecule in the cell

Plasmids: carry additional genes, eg. Antibiotic resistance genes

Who has Eukaryotic cells

Animals

Plants

Fungi

Protoctista

What is the structure of Mitochondria

Double membrane

Inner membrane is folded to form cristae to increase surface area for the attachment of enzymes that are used in aerobic respiration

Circular DNA and 70S ribosomes

What is the function of Mitochondria

Synthesise ATP during aerobic respiration and produce most of the ATP in eukaryotic cells

What is the structure of rough endoplasmic reticulum

Series of flattened membrane-bound sacs which are joined at some points to the nuclear envelope

Covered in ribosomes

Function of Rough endoplasmic reticulum

Transport polypeptides synthesised by the ribosomes to the golgi body

The ends pinch of to form transport vesicles containing polypeptides which then fuse to form golgi bodies

What is the structure of ribosomes

Two subunits each containing RNA- rRNA and proteins

What is the function of ribosomes

Carry out translation stage of protein synthesis

Translate the code carried by mRNA

Structure of the Golgi body

Series of flattened membranr-bound sacs called cristernae

What is the function of the golgi body

Polyleptide’s are modified and processed

Proteins are packed and secreted as vesicles or lysosomes

What is the structure of the nucleus

Two membranes forming the nuclear envelope

Nuclear pores enable communication between the nucleus and cytoplasm

Chromatin is made from DNA

Contains one nucleolus

What is the function of the nucleus

DNA in the chromosomes carries genetic code which codes for polypeptides

Responsible for controlling cell activities

What is the structure of the nucleolus

Condensed chromatin

What is the function of nucleolus

Responsible for synthesis of ribosomal RNA and the production of ribosomal sub-units

What is the structure of centrioles

9 sets of three microtubules

Function of centrioles

Produce and organise the spindle fibres that control cell division in animals

What is the structure of chloroplast

A double membrane with membrane bound sacs inside

Internal membrane form structures called thylakoids which are stacked to form grana

Starvh grains may be present

What is the function of chloroplast

Photosynthesis

What is the structure of plasmodesmata

Channels of cytoplasm that pass from one plant cell to another through the cell wall

What is the function of plasmodesmata

Enable substances to diffuse directly from one plant cell to another

What is the structure of vacuoles

Fluid fulled sac surrounded by a membrane called the tonoplast

Fluid is cell sap

What is the function of vacuoles

Stores water, nutrients and waste

When turgid vacule pushes against cell membrane

Define exocytosis

The secretion of substances from cells

It adds new membrane by fusion of vesicles which increases the surface area of the plasma membrane

Define endocytosis

Taking in substances/food particles by surrounding particles and infolding of the plasma membrane. This removed membrane from the plasma membrane and decreases the surface area

Define tissue

A group of similar cells carrying out the same function

Eg. Meristem tissue, epithelial

Define organ

A group of several tissues which carry out a function for the whole organism

Eg.eye, roots,leaves

Define organ system

Groups of organs that work together to carry out a function

Eg. Digestive system

Define connective tissue

Tissues that join one part of the body to another

Examples of connective tissue

Tissue in tendons

Skin

Blood cells

Bone