Understanding Genetic Information and Cell Processes

Genetic information → 1,8 genetic information pack in the nucleolus.

The DNA is packed around proteins called histones

Histone form nucleosome → 8→ 4

Nucleosomes form coils and the coils form supercoils.

Supercoils together called chromatin are packed and you don’t have access to the information.

 → Telomere: Repeats, act sort of biological clock being whittled down. 

 →Centromere(middle): highly condensed, also repetitive sequence, region where spindle fibers attach pulling chromatids apart during mitosis (kinetochore) → protein

→ Sister chromatids: the same information is copy.

→ Sister chromatids: same information and copy of the other 2 chromosomes make a copy and form the chromatid sisters.

→ Gene: segment of DNA or RNA in some viruses that codes for a protein.

→ Genome: is the whole genes of the chromosomes in the organism or species particularity and the non-coding parts also (junk DNA).

→ Transcription and Translation 

Genes are copied and translated

It’s a language that uses 4 letters, nitrogenous bases and they complement each other, ARN uses also 4 but uracil substitutes thymine.

DNA strands are antiparallel and complementary (nitrogenous bases).  

20 different amino acids to build up all the proteins.

→ Transcription: (copy of the DNA)

The transcription is the copy of the DNA in the form of MRNA.

This is copy because the enzymes break down the normal.

The template strand: (copy) goes to 3’ to 5’, double helices open with helicase enzymes to make the copy.

Non-template strand: (non copy) the transcription they do in the nucleolus.

RNA polymerase is going to read the copy of the template strand and make it in the form of MRNA.

Is a chain of MRNA complementary to the template strand, and this is going to be antiparallel in the form of RNA 5’to 3’.

-There are regions of the DNA that start a promoter with TATA BOX, they indicate the proteins when the genes start junk DNA.

-Terminator indicates when it finishes the genes and junk DNA.

→ Translation: 

When the MRNA is finish it has to travelled to the ribosomes, but is a dangerous trip, so the MRNA is must be protect, mature, it’s cleaned, review to see any error and they put caps(tapones), so is protected on the trip to the ribosomes, and is send to the ribosomes (RER).

Ribosomes have two parts (lower and upper assembled) and have two spaces and then the MRNA is read in the ribosome 5’to 3’.

MRNA is read in groups of three nitrogenous bases called codons; the codons have a complementary anticodon by the TRNA.

The peptide bonds join the 2 amino acids.

MRNA moves 3 peptide bonds, break the second 3 they have read and go away.


1 Codon→ TRNA→ Anticodon→ Amino acids.

2 Another TRNA→ Breaks and go away

MRNA moves 3 nitrogenous bases 

TRNA is the second moved to the first

When all is read, the ribosome break down

Translation is made in the nucleolus and the copy is made there.


-M: mitotic place

-G1: growth and normal metabolic roles.

-S: DNA replication / Synthesis place

-G2: Growth and preparation of mitosis

-G0: cell goes to G0 and it differentiates and specializes.

→ DNA replication:

The DNA replication is the process that allows the DNA to replicate, synthesize and identical copy. Out of an original helix you obtain two copies, two clones. 

This is the base of genetic heredity.

1 The DNA is opened by the helicase and the strand 3’to 5’is going to be read by the DNA polymerase. It’s read without stopping.

2 The 5’to 3’strand also is read by the helicase but it has to be read in the opposite direction it’s open. But it has to stop because the other strand has gone farther so this has to stop and go farther. These fragments are called ligase .

3 In the end you have a DNA copy.

2 DNA’S → 1 strand original / other strand copy

DNA polymerase → is a copy of RNA

→ Mitosis:

It’s a cellular division, cell divide in nucleus, it’s contents, in a process called mitosis and then the cytoplasm in a process called cytokinesis. Two identical diploid daughter cells are produced out of a mother cell.

0- Interphase: Nucleolus and the nuclear envelope are distinct and the  chromosomes are in the form of a threadlike chromatin.

1- Prophase: The nucleolus disappears because the genetic material (chromosomes) start to condense into chromosomes.

The centrosomes start to separate and the mitotic spindle starts to form.

2-Prometaphase: The chromosomes go to the poles.

The nuclear membrane dissolves and this marks the start of prometaphase.

Proteins attach to the kinetochores.

Chromosomes begin moving.

3-Metaphase: The spindle fully develops and chromosomes align at the metaphase plate.

4-Anaphase: The chromatin sisters separate and begin moving to opposite ends of the cell.

Spindle fibers not connected to chromatids lengthen and elongate the cell.

At the end, each pole contains a complete compilation of chromosomes.

5- Telophase and Cytokinesis: The nuclear membrane reforms, nucleoli reappears, chromosomes unwind into chromatin.

A protein filament ring contracts to cut cleave cells in two.

Later the protein synthesis.

→ Meiosis: 

4 cells with half of the genetic materials, form sexual cells (gametes)

1- Prophase 1: centrosomes go to the poles, the nuclear envelope starts breaking down and the chromosomes condense.

Crossing over occurs recombination > process with a homologous pair that part of the sister chromatids are mixed and they form 4 chromatin that are different.

2- Metaphase 1: The centromeres are in the poles, attach to the kinetochores, the fibers attach to the metacores = equal to the other.

3- Anaphase 1: The homologous chromosome moves to the poles one of the two chromosomes it joins whole.

4- Telophase and Cytokinesis 1: contractile rings and chromosomes gather at the poles of the cells and cytoplasm divides.

5- Prophase 2: a new spindle forms around the chromosomes and goes to the poles.

6- Metaphase 2: Spindle attach and align in the metaphase.

chromosomes are attached to the spindle > attach on both sides of the chromosomes.

7- Anaphase 2:  Centromeres divide and chromatin moves to the opposite poles.

8- Telophase and Cytokinesis 2: nuclear envelope forms around each set of chromosomes and cytoplasm divides.

4 cells and genetic materials are different and half.

→ Sexual reproduction and meiosis:

-Sexual reproduction : two parents combines (production of gametes)

4 call different information → recombination 

Asexual: unicellular living things and plants.

Parthenogenesis→ insect or reptiles 

Binary fission


Fragmentation→ when a part it’s cut, we later have for 2 warm.





high genetic variability facilitates adaptation “speeds”evolution

saves energy courtship is a non-issue greatest increase in fitness for each individual.


Energy costly 

courtships is time/ resource consuming 

usually sacrifies the fitness of one sex to other 

Low genetic variability adaption to environment difficult “retards”evolution.

→ Gene mutation:

Gene: information that goes for a protein

Locus; place on a chromosome for a gene mutation

Allele: Gene different variation of a gene mutation.

(Dominant: express / Recessive: not) 

-Gene: colour of the eye

.Variation: 3 colours.


– If they have the same allele in both/ Homozygous. (dominant)

-If they have different alleles in both/ Heterozygous. (recessive)

 –Genotype: all the genetic makeup of the organism.

-Phenotype: physical appearance of the organism.

-Phenotype= genotype+environment

→ Mutation: key point

-all new alleles originated by mutation

-New alleles introduce genetic variation: the raw material on which natural selection can act.

-Most mutations occur in somatic cells and are not inherited.

→ Fitness of mutation:

The fitness of a mutation describes its value to the survival and reproductive success of the organism.

-They can be:

  1. Lethal: many mutations are lethal and embryos are not-viable.

  2. Harmful: Non-lethal mutations

  3. Silent: most point mutations are probably harmless, with no noticeable effect on the phenotype.

  4. Beneficial: best observed in species with short generation times

  5. Neutral: they can be neutral at first but beneficial in the future.

-Deleterious mutation: can change the function of the protein having a negative impact on the organism, diminishing its capacity to survival. they are bad, but they don’t kill you.

– Accumulation of mutations: is the cause of aging, some can cause the apparition of a cancerous tumor, others can cause malformations of the fetus and the other can cause the death of the fetus.

→ Mutations (cancer)

  • Radiation

  • Alcohol

  • Drugs

  • Hormones

  • Cigarette

  • German measles

  • Lead mercury.