All units for biology

Cell cycle

A cell’s life

Why divide and now grow larger

DNA overload

Exchange for material

Materials must pass through the cell membrane and if the cell is too large, it cannot efficiently exchange materials.

Surface area to volume

The bigger the cell gets, the harder it is to move things or get things.

Cell division

A cell divides into 2 daughter cells

Chromosomes

tightly wound DNA + protein. Carries genetic information in eukaryotic cells and only during cell division.

Cell cycle process

G1, S, G2, M

PMAT

Prophase, metaphase, anaphase, telophase.

G1 phase

first stage of interphase, where the cell grows, carries out normal functions

S phase

where DNA is replicated, ensuring that each daughter cell will receive an identical set of chromosomes.

G2 Phase

is when the cell grows, synthesizes centrioles, and checks for DNA errors before entering mitosis.

Why some cells don’t replicate

They need to continue their function in the body

Mitosis

division of the nucleus

Prophase

chromosomes become visible, the nuclear membrane breaks down, and the spindle fibers start to form.

Metaphase

chromosomes align in the center of the cell, called the metaphase plate, preparing for separation

anaphase

sister chromatids are pulled apart toward opposite poles of the cell

telophase

chromatids reach the poles, the nuclear envelope reforms around each set of chromosomes, and the cell begins to split into two

cytokinesis

cytoplasm divides, resulting in two separate daughter cells, each with its own nucleus and organelles.

Contact inhibition

cells stop growing or dividing when they touch

Cyclins

proteins that regulate the cell cycle, which control the progression of the cell through different phases (checkpoints)

Stem cells

Unspecialized cell which can produce other cell types

Uncontrolled growth

rapid and abnormal division of cells, often seen in cancer, where the usual regulatory mechanisms fail, leading to tumor formation

Cytokinesis in Plants

a cell plate forms in the middle and develops into a new cell wall, splitting the cell into two

Cytokinesis in Animals

the cell membrane pinches in the middle, forming cleavage furrow that divides the cell into two daughter cells

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

Meiosis

Making of gametes

Prophase 1

homologous chromosomes form tetrads and exchange alleles through crossing over. The nuclear membrane then dissolves.

Metaphase 1

Homologous chromosomes align on the metaphase plate, and spindle fibers attach to the centromeres.

Anaphase 1

homologous chromosomes separate and sister chromatids move to opposite poles (2n → 1n).

Telophase 1

sister chromatids (now non-identical) decondense, the nuclear membrane forms, and centrioles prepare for the next stage.

Prophase 2

Non- identical sister chromatids condense, the nuclear membrane reforms, and centrioles begin to move apart, forming spindle fibers.

Metaphase 2

Non identical sister chromatids align on the metaphase plate, and spindle fibers attach.

Anaphase 2

non identical sister chromatids separate and move to opposite poles.

Telophase 2

chromatids decondense, the nuclear membrane forms, and the cleavage furrow begins to develop.

How many times cytokinesis happens in meiosis

1

2 bonds

How many bonds there are between A and T

3 bonds

How many bonds there are between C and G

Chargaff’s Rule

% of A = % of T / % of C = % of G

No phosphate at the end

3’

Has a phosphate on the end

5’

Helicase

unwinds and separates the DNA double helix, creating two single strands for replication

SSB Proteins

bind to the separated DNA strands, preventing them from recoiling or rejoining during replication.

Primase

synthesizes a short RNA primer that provides a starting point for DNA polymerase to begin building the new DNA strand.

Leading strand

synthesized continuously in the 5' to 3' direction, moving towards the helicase.

Lagging Strand

synthesized in the 3' to 5' direction in Okazaki fragments, which are later joined together.

DNA ligase

joins Okazaki fragments on the lagging strand, sealing the sugar-phosphate backbone to complete DNA replication. (glue)

Proof reading

process where DNA polymerase checks for errors during replication, correcting any mismatched bases to ensure accurate DNA synthesis.

DNA polymerase

synthesizes new DNA strands by adding nucleotides to a growing chain and also proofreads to correct errors during replication.

Where eggs and sperm are produced

overties and testicles

Spermatogenesis

the production of sperm, where excess organelles and cytoplasm are removed, and proteins form the flagellum.

Oogenesis

produces 1 egg and 3 polar bodies, with the egg containing cytoplasm and organelles. It undergoes meiosis I in each cycle, and meiosis II only completes if the egg is fertilized.

Polar bodies

Small cells with only DNA

Gene Variation

occurs through crossing over, independent assortment, and random fertilization.

Cytokinesis (meiosis)

where the cytoplasm divides, resulting in four genetically unique haploid cells, each with half the chromosome number of the original cell.

3’ to 5’

whether if it’s the leading strand or lagging strand, it always goes from a _____ direction

Allele

Variations of a trait

Gene

specific part on a chromosome that codes for a trait

Monohybrid

A genetic cross between two organisms that differ in a single trait (such as eye color or flower color).

dihybrid

A genetic cross between two organisms that differ in two traits, examining the inheritance of both simultaneously.

co-dominance

A situation where two different alleles for a gene are both expressed in the phenotype of the organism, with neither allele being dominant over the other.

Incomplete dominance

A genetic situation where neither allele is completely dominant over the other, leading to an intermediate phenotype.

genotype

The genetic constitution of an organism, representing the combination of alleles inherited from both parents.

phenotype

The observable physical or physiological traits of an organism, determined by its genotype and environmental factors.

dominant

An allele that expresses its trait even when only one copy is present in the genotype. It is represented by a capital letter.

recessive

An allele that only expresses its trait when two copies are present. It is represented by a lowercase letter.

Heterozygous

An organism with two different alleles for a particular gene (e.g., Aa).

Homozygous

An organism with two identical alleles for a particular gene (e.g., AA or aa).

sex linked traits

Traits that are determined by genes located on the sex chromosomes, often the X chromosome, leading to different inheritance patterns in males and females.

blood type

Blood type is classified by the presence or absence of specific antigens on red blood cells, with types A, B, AB, and O, determined by the ABO gene system.

Heredity

The process by which traits are passed from parents to offspring through genes

Father of genetics

Gregor Mendel, an Austrian scientist, established the foundation of genetics through his pea plant experiments.

P generation

The parent generation in a genetic cross. This consists of the two individuals that are crossed to produce the F1 generation.

F1 generation

The first generation of offspring resulting from a cross between two organisms from the P generation.

genotype

The genetic makeup of an organism, representing the specific alleles inherited from both parents. It determines the potential traits an organism can express.

autosomal dominance

A genetic trait where one copy of a gene from either parent can cause a condition, with a 50% chance of passing it on.

autosomal recessive

A genetic trait that requires two copies of the mutated gene (one from each parent) to show a condition. If only one copy is inherited, the person is a carrier but does not have the condition.

What does each chromosome code for?

Each chromosome codes for different traits.

traits

Observable characteristics or features of an organism, such as eye color, height, or blood type, determined by genetic information.

Gel Electrophoresis

Separating DNA by size

PCR

Polymerase Chain Reaction

Cell Differentiation

Specialization of cells

Stem Cells

Unspecialized cells that can rise to other cell types

Importance of Gel electrophoresis

It organizes DNA by its size degerming the presence or absence of certain genes

Importance of PCR

This process can help replicate DNA at a much faster rate

Taq Polymerase

A heat-resistant polymerase that came from a thermophile

step 1 of PCR

Temperature rises 94c and denatures DNA

step 2 of PCR

Temperature drops to 50c for primers

step 3 of PCR

Temperature rises to 72c for polymers

1 Billion strands of DNA

What 30 cycles of PCR results in

Faster

Smaller pieces move

slower

Larger pieces move

What all cells have

genomic equivalence and DNA

Transcription Regulation

This turns off or on certain expressions in the gene

Totipotent

Can become any cell type

Multipotent

Can become any cell in an organ group