Alevel Biology Unit 1 Cell Structure and Function

Information regarding in depth structure and function of cell organelles. Basics of bacteria and virus. According to 2025 -2027 A level Biology

Cell

Basic structural and functional unit of all living things

Two Types of Cell

Prokaryotes and eukaryotes

Size of prokaryotic cell

1-5umin diameter, typically smaller than eukaryotic cells.

Size of animal cell

20um

Size of plant cell

40 um to 100 um in diameter, generally larger than animal cells.

Prokaryotic cells always have a cell wall made of ——————-.

peptidoglycan.

Prokaryotes and Eukaryotes divide by different mechanisms called

Eukaryotes by mitosis and prokaryotes by binary fission.

What is the organelle that all eukaryotes have but prokaryotes do not?

Nucleus and membrane-bound organelles Like Endoplasmic reticulum, Golgi body and mitochondria

What are the structures found in all Bacteria?

Cell membrane, cytoplasm, 70s ribosomes, and circular DNA

What the structures found in some bacteria but not all?

Pili or Fimbriae, flagella, plasmids, cell wall, and slim capsule

Cell wall of bacteria is made of——————.

Murein

Circular DNA

Double stranded DNA joined at ends to create a loop usually found in prokaryotes.

Plasmids

Small Circular DNA molecules which have genes for anti-biotic resistance

Pilli or Fimbriae

Help with attachment to surfaces and other cells. Also help in Reproduction.

Virus

Non cellular structure with a nucleic acid core

Viruses have a protein coat made of ————————.

Capsid which has subunits capsomeres.

Outer envelope of some viruses is made of?

Phospholipids

Liquid substance in a cell is called

Cytosol

Double membrane organelles

Nucleus, chloroplast, Mitochondria

Single membrane organelles

Sap Vacuole, Golgi Body, Endoplasmic reticulum

Substances leaving the nucleus from the nuclear pore

mRNA and Ribosomes

Substances entering Nucleus from Cytoplasm

Proteins to make:

1) Ribosomes

2)Nucleotides

3)ATP

4) Hormones like Thyroid Hormone T3.

Chromosomes

Contain DNA which is organized into functional units called genes that control the activity of the cell and inheritance

Site of protein synthesis

Ribosomes and Rough Endoplasmic Reticulum

Site of transcription and mRNA production

Nucleus

Site of ribosomal synthesis

Nucleolus (inside the nucleus)

Chromatin

DNA and its associated proteins

Size of cell wall, cell membrane and nucleus

2um,7nm,7um respectively

Endoplasmic Reticulum form —————— compartments called, ————-.

flattened, sacs

Rough endoplasmic reticulum has ——————- but Smooth Endoplasmic Reticulum does not.

Ribosomes.

70s Ribosomes are found in all prokaryotes and in ————————- and ————————- of eukariyotes.

Mitochondria and Chloroplast

Ribosomes made of two subunits called

large subunit and small subunit

Size of 70s and 80s ribosomes

18nm and 22nm respectively

Function of Rough endoplasmic Reticulum VS Function of Smooth endoplasmic reticulum

RER = Site of protein synthesis and protein modification

SER = site for lipid and cholesterol synthesis

Euchromatin

loosely packed form of DNA and transcriptionally active (lightly stained under microscope)

Heterochromatin

Tightly packed form of DNA Transcriptionally inactive. (Deeply stained under microscope.)

Golgi boby

Stack of flattened sacs.

Golgi body formed by?

Transportation vesicles from RER on cis face

Golgi Body broken down to form?

Secretory vesicles and lysosomes on trans face

4 major roles of Golgi Body

Hint: ( Mia Paid For the Frogs:))

1) Modification of proteins and lipids. (like addition of phosphate group)

2) Packaging molecules into vesicles for transport

3) Formation of secretory vesicles to transport protein out of cell

4) Formation of lysosomes

Which amino acid is removed in golgi body from newly formed proteins to make them functional?

The first amino acid …… methioene

Role of golgi body in plants

converts sugar into cell wall components

Size of golgi body

7nm each cisterna

Size of Lysosome

1um

Lysosomes are ———— membraned, ——————sacs containing ———————- enzymes that work in —————- conditions. Example of these is ———————— present in sperms.

single, spherical, hydrolytic, acidic, acrosomes.

In ———————-, lysosomes digest bacteria in a process known as———————-.

White blood cells, Phagocytosis

Site of synthesize of ATP

Mitochondria

Mitochondria divides by —————.

Binary fission

A mitochondria’s inner fold form finger like projections called ————— which project into interior solution called ——————.

cristae, matrix

outer membrane of mitochondria has transport protein called————.

Porin

inner membrane of mitochondria has more ——————- barrier

selective

where does respiration occur and what is supplied to the reaction?

matrix solution and inner cristae. Hydrogen electrons with help of enzymes supplied.

Energy is released by breaking ATP into ————- in a —————- reaction. This is then —————- in the mitochondria to form ATP during ———————.

ADP, hydrolysis, recycled, respiration

cell surface membrane has a ——————————— appearance

Trilaminar

Light Dependent reaction in chloroplast and its location

Light energy absorbed and water is used to synthesize ATP.

occurs in thylakoid

Light Independent reactions in chloroplast and location

ATP used to covert Co2 into glucose also called co2 fixation. occurs in Stroma.

Arrange in proper order lamella, grana, and thylakoid

Lamella- single membrane in chloroplast

Thylakoid- fold in membrane

Granna- stack of folds in membrane

Microtubules are made of a protein called —————-. which has two types —————- and ———— tubulin. These two join together to form a —————. These join together end to end to form a long —————————-. ———- of this line up to form a ring.

Tubulin, Alpha, Beta, dimer, protofilament, 13

microtubules are the ———————— transport system as vesicles and organelles can move along their surface.

intracellular

microtubules form —————- in cell division to separate chromosomes and—————.

spindle fibres, centrioles

Microtubules along with ——————- filament form the cells ————.

Actin, cytoskeleton

Centrioles are ————- from most plant cells

absent

A centriole has a ————- centre and is made of ———————————— of microtubules.

hollow, nine triplets

microtubules for spindle formation are assembled by ——————-.

centrosomes

centrioles found at the base of cilia and ——————- known as ———————— extend microtubules which is vital for locomotion.

flagella basal bodies

Middle lamella contains substances like ——————— that glue substances to glue cells together.

pectin

Role of sap vacuole

1) support through turgor pressure

2)Lysosomal activity (contains hydrolytic enzymes)

3)Store nutrients

4)Store waste material

5)contains pigments

6) contain latex or calcium oxalate to avoid herbivores

Axoneme

cylinder of microtubules arranged in 9+2 arrangement

Nine—————- of microtubules make wall of axoneme present in cilia and flagella. Each duplet is made of two microtubules A and B. Microtubule A has complete ——— protofilaments while B is in complete and has ————- protofilaments.

duplet, 13, 10

When centrifuged in what order do organelles sediment?

nuceus——Chloroplast———-Mitochondria———RER—-Plasma membrane—-Ribosomes