DNA
OBJETIVES
We want to answer the following questions:
What is the structure of DNA?
Who / s discovered it and how? Which year?
How are sex cells formed? How is a zygote formed?
THEORY
(1st part) What is the DNA ?
What is the structure of DNA?
Deoxyribonucleic acid, or DNA, is a molecule that contains the instructions that an organism needs to nurture, relate and reproduce. These instructions are found inside each cell, and are passed down from parents to their children.
The instructions that determine all the characteristics and functions of an organism are found in its genetic material: DNA (deoxyribonucleic acid).
(2ND PART) Who discovered it and how?
Knowledge of structure and function was key to the development of modern biotechnology.
The double-stranded structure of DNA, which researchers James Watson and Francis Crick attributed to the discovery project in 1953. Thanks to physicist Rosalind Franklin, the creator of this project. Answers were provided to many questions about inheritance and about the self-replication of genetic material and the idea that genetic information was within the sequence of the bases that make up DNA.
As time passed, it was observed and investigated that it was possible to determine that all living beings contain similar DNA, formed from the same units: nucleotides. This genetic code by which cellular instructions are "written" is common to all organisms. In other words, the DNA of a human being can be "read" inside a bacterium, and a plant can interpret the genetic information of a different plant. This property of genetic information is known as "universality of the genetic code."
This is the Timeline Padlet: padlet.com/bacilus2015/82tednk8vomzskow
(3RD Part) How are sex cells and Zygote formed ?
A)How are sex cells formed ?
The formation of sex cells is a central part of human reproduction: In fertilization, an egg cell and a sperm cell combine. These sex cells are also called reproductive cells or gametes. Sperm cells are produced in men's testicles and egg cells are produced in women's ovaries. Sex cells are different from other cells in one special way: Put simply, they only have one half of the total amount of human genetic information. When a sperm cell fertilizes an egg cell, the resulting cell has a full set of genetic information again.
Sex cells are formed through a particular kind of cell division called meiosis. Unlike in normal cell division (mitosis), the genetic material of the original (parent) cell is divided up twice.
As in most other cells in the body, the nucleus of the original cell contains the person's full set of genetic information. This information is stored in the form of long threads (strands) of DNA – in the chromosomes.
Before the original cell divides for the first time, all the genetic material is reproduced: a copy of each chromosome is made. In prophase
The DNA strands become more tightly packed into a condensed form (DNA is condensed in prophase I) (and can be seen under a microscope not yet). Each chromosome and its copy remain attached in one place. You have to improve
As in many other living things, chromosomes in humans always come in pairs.
Unlike "normal" cell division (mitosis), in meiosis the chromosome pairs are aligned first along the center of the cell. And the comatids are separated to create a new cell.
The pairs separate there. The individual chromosomes then move to opposite sides of the cell, together with their attached copy. The cell membrane starts pinching inward to form two separate cells.
A second cell division follows: The copies of the chromosomes separate.
So the parent (original) cell gives rise to four sex cells. The nucleus of each sex cell contains half of the original genetic material.
In men, these cells develop into sperm cells.
In women, only one of the four sex cells becomes an egg cell that can be fertilized. During meiosis, it receives most of the cell body of the parent cell. The three smaller cells – referred to as polar bodies – break down and disappear.
If a sperm cell fertilizes an egg cell, the nuclei of the two cells combine.
A new cell with a complete set of genetic information is produced – one half is from the mother, and the other half is from the father. The fertilized egg cell can now start developing into a baby.
B) How are zygote formed ?
Zygote are fertilized egg cell that results from the union of a female gamete (egg, or ovum) with a male gamete (sperm). In the embryonic development of humans, the zygote stage is brief and is followed by cleavage (Cleavage is the first few cellular divisions of a zygote), when the single cell becomes subdivided into smaller cells.
The zygote represents the first stage in the development of a genetically unique organism. The zygote is endowed with genes from two parents, and thus it is diploid (carrying two sets of chromosomes). The joining of haploid gametes to produce a diploid zygote is a common feature in the sexual reproduction of all organisms except bacteria.
The zygote contains all the essential factors for development, but they exist solely as an encoded set of instructions localized in the genes of chromosomes. In fact, the genes of the new zygote are not activated to produce proteins until several cell divisions into cleavage. During cleavage the relatively enormous zygote directly subdivides into many smaller cells of conventional size through the process of mitosis (ordinary cell proliferation by division). These smaller cells, called blastomeres, are suitable as early building units for the future organism.
In humans, identical twins develop from a zygote that splits into two separate cell masses at a relatively early stage in its growth. These two masses, which are genetically identical to each other, go on to become embryos. Fraternal twins, by contrast, develop from two separate zygotes (two separate eggs fertilized by two different sperm).
MEIOSIS PROCEss:
MEIOSIS I:
Prophase I:
All chromosomes roll up. Then, homologous chromosomes pair up and exchange fragments of genetic material. The nuclear membrane and the nucleolus disappear and each centriole moves towards a pole. Spindle formation begins.
Metaphase I:
The chromosomes are arranged in pairs on the equatorial plate (this is the only phase where the chromosomes are clearly seen under a microscope).
Anaphase I:
The mitotic spindle contracts and drags the chromosomes to each pole to separate them. An error in this process can cause alterations in the number of chromosomes of the resulting cells.
Telophase I:
The mitotic spindle disappears and two new nuclei are formed with their nuclear membrane. The chromosomes despiralize and cytokinesis occurs.
Meiosis II:
This second process is basically a mitotic division but with the difference that the cells are haploids. Its fases are: prophase II, metaphase II, anaphase II, telophase II and cytokinesis. In this division, the chromatids are the ones that separate. As a final result, we have four haploid cells.
The resultant cells are completely different as the original cell.
EXPERIMENT
This is the experiment we did that consist in the DNA abstraction from a fruit.
drive.google.com/file/d/1cU5iDyIRaCG-fd0b27tRKrU-rHDX4VmG/view?usp=sharing
In this experiment, the detergent breaks down the cell membrane by dissolving the lipids and proteins of the cell and disrupting the bonds that hold the cell membrane together.
And the salt allows the DNA to precipitate in a cold solution of alcohol.
MODEL
Here we can see an image of our model. This one represents the process of meiosis.
KAHOOT
PERSONAL OPINION:
What we have learn?
Aina: I learned a lot about the process of meiosis and the structure of DNA. I have also improved my skills to edit videos and create models.
Paula: I learned to the other things of the structure of DNA and about scientists that discovered it.
Simon: I learned the existence of James Watson and Francis Crick.
What we want to improve in this activity?
Aina: I would like to improve the same as in the other challenge: communication and participation, since it has been pretty difficult to do everything with so few participants. I hope the next challenges go better!
Paula: I want to improve my expression when writing in English and also to continue working as a team.
Simon: We can improve the communication between us. It was the
What is the best thing for us?
Aina: For me, the best part is the video editing as I really enjoy doing it!
Paula: What I liked the most was doing the experiment in the laboratory of my institute.
What have we done?
Objectives: Aina
Theory:
(1st part) What is the DNA? : Paula
(2nd part) Who discovered it and how? : Paula
(3rd part) How are sex cells and Zygote formed ? : Simon
Meiosis process: Aina
Experiment:
Realization: Aina and Paula
Edition: Aina
Model: Aina
Kahoot: Paula
Aina, Paula & Simon