Samenvatting
Samenvatting DNA & Evolutie
- Vak
- DNA & Evolutie
- Instelling
- Avans Hogeschool (Avans)
hier is een zelfgemaakte samenvatting van DNA en Evolutie. Ik heb dit vak afgerond met een 7,3. Hopelijk jij ook!
[Meer zien]Voorbeeld 4 van de 59 pagina's
Voorbeeld 4 van de 59 pagina's
In winkelwagengesponsord bericht van onze partner
Verkoper
VolgenVoorbeeld van de inhoud
DNA en Evolutie13.1 – Offspring acquire genes from parents by inheriting
chromosomes
Inheritance of genes
• Genes: A discrete unit of hereditary information consisting of a specific nucleotide
sequence in DNA.
- Program specific traits that emerge as we develop from fertilized eggs into adults.
• Most genes program cells to synthesize specific enzymes and other proteins, whose
cumulative action produces an organism’s inherited traits.
• Gametes; reproductive cells that transmit genes from one generation to the next.
• During fertilization, male and female gametes (sperm and eggs) unite, passing on
genes of both parents to their offspring.
• 46 chromosomes in their somatic cells.
• Locus; A specific place along the length of a chromosome where a given gene is
located.
• Genome; consists of the genes and other DNA that make up the chromosomes we
inherited from our parents.
Comparison of Asexual and sexual reproduction.
• In Asexual reproduction a single individual is the sole parent and passes copies of all
its genes to its offspring without the fusion of gametes.
- The genomes of the offspring are exact copies of the parent’s genome.
• Clone; A group of genetically identical individuals.
• Sexual reproduction: Two parents give rise to offspring that have unique
combinations of genes inherited from the two parents.
- Offspring vary genetically from their siblings and both parents.
13.2-fertilazation and meiosis alternate in sexual life cycles
Life cycle:
The generation-to-generation sequence of stages in the reproductive history of an organism
from conception to production of its own offspring.
Sets of chromosomes in Human cells
• Each somatic cell has 46 chromosomes.
• During Mitosis, chromosomes are condensed → can be distinguished from one
another.
• Two chromosomes of each 23 types.
, • Karyotype; A display of the chromosome pairs of a cell arranged by size and shape.
• Homologous chromosomes; two chromosomes of a pair have the same length,
centromere position and staining pattern.
• Both chromosomes of each pair carry genes controlling the same inherited
characters.
• Human females → homologous pair of X chromosomes (XX)
• Males → X chromosome and Y chromosome (XY)
- Sex chromosomes
• Others → autosomes
• We inherit one chromosome of a pair from each parent.
- A maternal set from our mother and a paternal set from our father.
• Diploid cell; Any cell with two chromosome sets.
- 2n (2n = 46)
• When chromosomes are duplicated → still diploid (2n)
• Haploid cells; Gametes which contain a single set of chromosomes.
- n (n = 23)
- 22 autosomes plus single sex chromosome.
Behavior of chromosomes sets in the human life cycle
• Human life begins with a haploid sperm from the father and a haploid egg from the
mother.
• Fertilization; The union gametes, culminating in fusion of their nuclei.
- Zygote; fertilized egg → diploid.
• Mitosis of the zygote and its descendant cells generates all the somatic cells in the
body.
- Chromosomes sets + genes are passes with precision to the somatic cells.
- Gametes are not produced by mitosis.
• Gametes develop from specialized cells (germ cells) in the gonads; ovaries in females
and testes in males.
• Meiosis; type of cell division that reduces the number of sets of chromosomes from
two to one in gametes, counterbalancing the doubling that occurs at fertilization.
- Each human sperm and egg is haploid (n = 23)
, - Fertilization restores the diploid condition by combining two sets of
chromosomes and the human life cycle is repeated, generation after generation.
• Fertilization and meiosis alternate in sexual life cycles, maintaining a constant
number of chromosomes in each species from one generation to the next.
The variety of sexual life cycles
• Gametes are the only haploid cells.
• Meiosis occurs in germ cells during the production of gametes, which undergo no
further cell division prior to fertilization.
- After fertilization, the diploid zygote divides by mitosis, producing a multicellular
organism that is diploid.
• Alternation of generations; second life cycle of plants and some species of algae.
- Sporophyte; the multicellular diploid stage.
*Meiosis produces haploid cells → spores
*spores doesn’t fuse with another cell
*divides mitotically
- Gametophyte; multicellular haploid stage.
* Cells give rise to gametes by mitosis
* Fusion of 2 haploid gametes at fertilization results in a diploid zygote.
- The sporophyte generation produces a gametophyte as its offspring
- The gametophyte generation produces the next sporophyte generation.
• Third life cycle → in most fungi and protists.
- After gametes fuse and form a diploid zygote, meiosis occurs without a
multicellular diploid offspring developing.
- Meiosis produces not gametes but haploid cells that then divide by mitosis and
give rise to either unicellular descendants (nakomelingen) or a haploid
multicellular adult organism.
- Haploid organism carries out further mitoses, producing the cells that develop
into gametes.
- Diploid stage → single-cell zygote
• Either haploid and diploid cells can divide by mitosis depending on the life cycle.
, 13.3 – Meiosis reduces the number of chromosomes sets from diploid
to haploid
Meiosis: Preceded by the duplication of chromosomes.
- Meioisis I
- Meioisis II
The two chromosomes of a homologous pair are individual chromosomes that were
inherited from each parent.
o Homologs may have different versions of genes at corresponding loci.
o Each version is called an allele of that gene.
Meiosis I
Prophase I:
o Spindle formation, nuclear envelope breakdown.
o Chromosomes condense
o Crossing over; The reciprocal (onderling) exchange of genetic material between
nonsister chroma-tids
- Chiasmata; X-shaped regions where crossovers have occurred.
o Microtubules from one pole or the other attach to the kinetochores, one at the
centromere of each homolog.
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper nathalieridderhof. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €7,39. Je zit daarna nergens aan vast.
Is Stuvia te vertrouwen?
4,6 sterren op Google & Trustpilot (+1000 reviews)
Afgelopen 30 dagen zijn er 67163 samenvattingen verkocht
Opgericht in 2010, al 14 jaar dé plek om samenvattingen te kopen