Biology Revision - Genetics, Cell Cycle, and Transport

299 practice flashcards covering cellular biology, genetics, and molecular inheritance based on lecture notes.

Somatic cells

Body cells that do mitosis. Diploids. Asexual reproduction

Gametes

Sperm and egg cells that do meiosis. Haploids. Sexual reproduction

Cytokinesis

The division of cytoplasm into two occurring along with mitosis. Starts in anaphase and ends in telephase.

Longest phase of the cell cycle

Interphase

Second longest phase of the cell cycle

prophase

Shortest phase of the cell cycle

anaphase

Mitosis (Definition)

Asexual reproduction in Eukaryotes. One mother cell produces $2$ daughter cells with the same DNA.

Cause for cell division (Nutrients)

If the cell gets too big, it gets harder to absorb nutrients.

Cause for cell division (Waste)

If the cell gets too big, it gets harder to remove waste.

Cyclin signaling

A signaling process that tells the cell to divide.

Cell Cycle stages

$G1$, $S$, $G2$, $M$

Interphase components

$G1$ phase, $S$ phase, $G2$ phase

M phase stages

Prophase, Metaphase, Anaphase, Start of cytokinesis, Telephase, End of Cytokinesis

G1 Checkpoint Location

Near the end of the $G1$ phase

G1 Checkpoint Factors

Checks for DNA damage, Growth factors, Nutrients, and Proper cell size

G2 Checkpoint Location

Near the end of the $G2$ phase

G2 Checkpoint Factors

Checks for Proper cell size and Proper DNA replication

M phase checkpoint Timing

During metaphase

M phase checkpoint Factor

Checks for Spindle alignment to chromosome

G1 phase

Growth/Gap $1$. The cells grows.

S phase

Synthesis. The DNA replicates and the chromosomes replicate into chromatids

G2 phase

Growth/Gap $2$. Prepares for mitosis

G0 phase

Growth/Gap $0$. The cell enters a resting state. The phase the cell is in if it fails the $G1$ checkpoint.

Checkpoints

Places where the cell cycle temporarily stops for a cell check.

Apoptosis

Process where the cell self destructs and undergoes death when DNA is damaged beyond repair.

Internal regulators

Proteins inside the cell that stop and start the cell cycle at checkpoints, such as cyclin and $p53$.

External regulators

growth hormones outside the cell that stop and start the cell cycle at checkpoints.

Cyclin

On switch. Control switch for cell cycle. Causes the cell to move from $G2$ to $S$ or $G2$ to $M$.

p53

Off switch. Blocks the cell cycle at $G1$ checkpoint if DNA is damaged so the cell can be repaired.

High levels of p53

Indicates more damaged cells; can cause apoptosis if DNA damage is severe.

Cancer

Disease where regulation of the cell cycle malfunctions and normal cell growth/function is lost.

Cancer Causes

Mutations in the proto-oncogene (genes for cyclin) or tumor suppressor genes (genes for $p53$).

Proto-oncogenes

Genes that code for the cyclin protein.

Tumor suppressor genes

Genes that code for the $p53$ protein.

Chromosome

Chromatin that is folded and coiled up during mitosis. Seen during mitosis, not seen during interphase.

Chromatin

Long thin fibers of DNA and histone proteins that are not folded/coiled in interphase. Seen during interphase.

Chromosome composition

DNA + histone proteins

Chromatid

Strands of identical chromosomal material that come in pairs. Half of a replicated chromosome attached to a centromere.

Centromere

The structure that attaches the two pairs of chromatids together like a knot.

Human chromosome count

$23$ pairs, totaling $46$ chromosomes.

Anaphase transition

Phase where chromatids start becoming daughter chromosomes and become fully separate from one another.

Spindle fiber contraction

Process occurring in anaphase that pulls the chromosomes toward opposite poles.

Actin fibers

Muscle protein fibers that do the pinching in of the animal cell in cytokinesis to form a cleavage furrow.

Cleavage furrow

The pinching in of an animal cell to create $2$ daughter cells. Part of cytokinesis in animal cells.

Kinetochore

Protein that attaches to the centromere and connects the spindle fiber to the centromere. Dissolves at the end of anaphase.

Cell plate

The disc-like structure that separates $2$ daughter cells and later forms part of the cell wall. Part of cytokinesis in plant cells.

Faulty spindle fibers

Will cause daughter cells to end up with the wrong number of chromosomes.

Down syndrome

Condition caused by daughter cells having the wrong number of chromosomes due to faulty spindle fibers.

Centrosome

Organelle that connects to spindle fibers and is attached to the cell membrane by aster fibers; contains $2$ centrioles.

Centriole

Cylinder that helps in the formation of spindle fibers during mitosis. Comes in pairs inside the centrosome; made by centrosomes.

Aster fibers

Star shaped spindle fibers attached to the cell membrane to keep everything in place and help chromosomes split properly.

Cancer vs Normal: Differentiation

Cancer cells are nondifferentiated (don’t turn into specialized cells), while normal cells are differentiated.

Cancer vs Normal: Apoptosis

Cancer cells do not undergo programmed cell death, while normal cells do.

Cancer vs Normal: Contact Inhibition

Cancer cells don’t stop growing when touching another cell, while normal cells do.

Cancer vs Normal: Metastasis

Cancer cells undergo the spread to other parts of the body, while normal cells do not.

Tumor formation cause

Cancer cells having no contact inhibition, causing cells to pile up on each other.

Metastasis

The process where tumors spread all over the body, forming new tumors.

Differentiated cell

A cell that has undergone the process to turn into a specialized cell.

Interphase visibility

Nuclear membrane and nucleoli are visible; centrosomes/centrioles are next to each other.

Early Prophase

Centrosomes move apart toward opposite poles, asters form, and double chromosomes become visible as long threads.

Middle Prophase

Spindle fibers form, centrioles move to poles, and $2$ chromatids attached to a centromere become visible.

Late Prophase (Prometaphase)

Nuclear membrane and nucleolus disappear; chromatids begin moving towards the equator.

Metaphase events

Centromeres lined up at equator and the $M$ phase checkpoint occurs.

Early Anaphase

Spindle fibers contract pulling chromatids apart into daughter chromosomes which begin to move apart.

Late Anaphase

Daughter chromosomes move apart to opposite poles.

Telophase events

Spindles and asters disappear, nuclear membrane and nucleoli reappear, and cleavage furrow forms.

Plant vs Animal: Centrioles

Animal cells have centrioles, while plant cells do not.

Plant vs Animal: Cell Wall

Plant cells have a cell wall, while animal cells do not.

Cell Membrane

Structure that controls what enters and exits the cell.

Fluid Mosaic Model

A model of the cell membrane that shows all its constituent parts.

Selectively permeable

Allows some molecules in and some molecules out based on structure, transport proteins, and the phospholipid bilayer.

Integral protein

Type of protein that is embedded in the cell membrane.

Peripheral protein

Type of protein that is not embedded in the cell membrane.

Glycolipid

Combination of a carbohydrate chain and a lipid (phospholipid).

Glycoprotein

Combination of a carbohydrate chain and a protein.

Channel proteins

Type of transport protein that is almost always open, specific to an ion or molecule, and used for passive transport.

Carrier proteins

Type of transport protein that changes shape to move molecules; can be active ($ATP$ required) or passive.

Cell recognition protein

Integral glycoprotein that identifies whether substances will harm the cell and sends alert signals.

Receptor protein

Integral protein that receives signals and transfers those signals inside the cell.

Enzymatic protein

Integral protein that acts like an enzyme to speed up chemical reactions.

Junction protein

Integral protein that allows cells of the same type to stick together in multicellular organisms.

Phospholipid Layer components

Phosphate group (head) and Fatty Acid (tail).

Cholesterol (Membrane)

System component identified as label E in the fluid mosaic model.

Transport protein (Definition)

Type of integral protein that transports molecules, macromolecules, and ions across the cell membrane.

Diffusion

The movement of a substance from high concentration to low concentration without energy.

Simple diffusion

Diffusion with no membrane required, such as red dye in a jar.

Facilitated diffusion

Diffusion across the cell membrane with the help of a transport protein, such as water in an aquaporin.

Active transport

Molecules moving from low to high concentration against the gradient, requiring energy usually as $ATP$.

Passive transport

Molecules moving from high to low concentration with the gradient, requiring no energy.

Direct crossers

Small molecules like water, carbon dioxide, oxygen, lipids, and amino acids that pass through the membrane via passive transport.

Bulk transport crossers

Large macromolecules that cannot directly cross and require active transport.

Cellular respiration formula

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + \text{energy (stored in ATP)}$$

Bulk transport process

Cell membrane dismantles, vesicles form around large molecules, and transport occurs via active transport.

Endocytosis

Taking bulky material into the cell by forming vesicles around it; includes phagocytosis and pinocytosis.

Phagocytosis

'Cell eating'; forms a vacuole around a molecule (like starch or bacteria) and digests it.

Pinocytosis

'Cell drinking'; forms a vacuole around and digests small liquids or extracellular fluid.

Receptor mediated endocytosis

Typified by receptor binding (e.g., cholesterol) followed by formation of a vacuole and fusion with a lysosome.

Exocytosis

Forcing material out of the cell in bulk by fusing a vesicle membrane with the cell membrane; used for hormones and waste.

Secrete vs Excrete

To secrete is to remove useful substances (hormones); to excrete is to remove useless waste.

Solute

Substance being dissolved in a solvent, such as sugar or salt.