NMAT Biology | Cells

Nucleus

Contains all of the genetic material needed for the replication of the cell; contains all of the DNA

The big boss

Mitochondrion

Location of metabolic processes:

• Pyruvate dehydrogenase

• Citric acid cycle

• ETC

• Oxidative phosphorylation

• B oxidation

• ATP production

The cell’s battery

Lysosomes

Membrane-bound structures that have hydrolytic enzymes capable of breaking down many different substances; sweepers that digest waste

Ribosomes

Synthesizes proteins; a protein factory

• Either free-roaming or attached to the rough ER

Rough Endoplasmic Reticulum

Studded with ribosomes and synthesizes proteins that are meant for insertion into a membrane or for secretion

Smooth Endoplasmic Reticulum

No ribosomes but does lipid synthesis and detoxification

Golgi Apparatus

Packages proteins; post-translational modification of proteins happen here

Peroxisomes

Break down fatty acids and destroy hydrogen peroxide

What does the fluid mosaic model show?

It shows that the membrane is flexible and that many proteins float around it

Phospholipids

Make the membrane with hydrophilic head and a hydrophobic tail

What do proteins in the membrane do?

Transport, act as receptors, and enzymes

What does cholesterol in the membrane do?

It keeps the membrane stable; doesn’t make it too rough or too flexible

What do carbohydrates in the membrane do?

They help in cell recognition

ex: blood groups

Diffusion

Moves from high concentration to low concentration with NO energy

Osmosis

Water moves from low solute to high solute

Water follows salt

3 Outcomes of Osmosis

Note:

• Animals: Hypertonic → crenation

• Plants: Hypertonic → plasmolysis

Active transport

Moves from low → high

• Needs ATP

ex: similar to going up a hill

Cytoskeleton

Acts as a skeleton inside the cell

• Helps in maintaining shape, allowing movement, and transport

Cilia

Many short hair-like structures

ex: Respiratory tract

Flagella

Few long tails

ex: Sperm cell

Cell theory

• All living things are composed of cells

• Cells are the basic functional unit of life

• Cells arise from preexisting cells

• Cells carry genetic information in the form of DNA

  • Genetic material is passed on from parent to daughter cell

Eukaryotes vs. Prokaryotes

Eukaryotes: True Cells; usually multi-cellular

• DNA is wrapped in histones

Prokaryotes: Primitive; usually unicellular

• Multiple proteins act together to fold and

  condense prokaryotic DNA

• Folded DNA is

  then organized into a variety of conformations

  that are supercoiled and wound around

  tetramers of the HU protein.

Classification of prokaryotes

1. Cocci: Spherical bacteria

2. Bacili: Rod-shaped bacteria

3. Spirilli: Spiral-shaped bacteria

Gram-positive bacteria

Cell wall of a prokaryote that has a lot of peptidoglycan

Gram-negative bacteria

Cell wall of a prokaryote that has little quantities of peptidoglycan with lipopolysacharides

Flagella purpose in prokaryotes

Contain a basal body that serves as the engine for motion

Binary Fission

Method of how prokaryotes divide

• They replicate and attach to the cell wall

• Cell wall grows along the midline and forms daughter cells

Cell Cycle

G1 → S → G2 → M

G1 (growth 1)

Cell living its normal life

• Grows bigger

• Make proteins

• Makes more organelles

S Phase (synthesis)

Cell copies its DNA

Before the S phase, a cell has 46 chromosomes

• After DNA replication, there are still 46 chromosomes but each have 2 sister chromatids

G2 Phase (Growth 2)

Cell checks everything after the S phase

• Grows more

• Makes proteins needed for mitosis

• Prepares for division

“Get ready” Phase

M Phase

When the cell divides

• After this, it goes to PMAT → cytokinesis (splitting of parent to 2 daughter cells)

Prophase

DNA condenses

• Chromosomes become visible

• Nuclear membrane disappears

Everything is basically packing up to leave

Metaphase

Chromosomes line up in the middle

Anaphase

Cell splitting apart

Telophase

New nuclei form and cell begins to return to normal

Homologous chromosomes

Carry the same genes but have different alleles (versions)

• Each have 2 sister chromatids

Prophase I (Meiosis)

1. Homologous chromosomes pair up and create a tetrad (4 chromatids)

2. Crossing over

• Chromosomes exchanging their parts

• this creates genetic variation

Meiosis

Spermatogenesis

Formation of sperm in meiosis

• 1 cell → 4 sperm (all functional)

Oogenesis

Formation of the egg in meiosis

• 1 cell → 1 egg (+3 polar bodies as only 1 becomes an egg)

Early Embryonic Development

After sperm meets the egg:

• Fertilization

• Zygote

• Cleavage

• Morula

• Blastula (Blastocyst)

• Implantation

• Gastrulation

• Neurulation

Cleavage

Mitotic divisions

• basically dividing and dividing

• Just like a pizza getting more slices— not getting bigger but more divisions

Morula

Outcome of many divisions

• Embryo now looks like a raspberry

Blastula (Mammals: Blastocyst)

Embryo becomes hollow

• Hollow space is called the blastocoel

Implantation

Blastocyst attaches onto the uterus

Gastrulation

3 germ layers form:

• Ectoderm: Nervous system + skin

• Mesoderm: Muscles + kidneys

• Endoderm: Internal organs

Neurulation

Nervous system starts to form

• Includes brain and spinal cord