Developmental Psychology
Problem 1-The Birds and the Bees
Genetic foundations
Genotype: The genetic information that an individual inherits which determines our species
and influences the unique traits/characteristics.
Phenotype: The way one person’s genotype is expressed in observable or measurable
characteristics.
Gametes
The sex cells, sperm and ovum.
Sperm cell →release its genetic material + Ovum →release its genetic material = a new cell
nucleus= zygote.
Chromosomes
Nucleus contains 46 chromosomes (23 pairs, 22 autosomal, 1 pair sex chromosomes-X long-
Y-short). One member of each pair comes from the ovum and one from the sperm.
Chromosomes are made up of DNA (deoxyribonucleic acid).
DNA
A complex double-helix model that looks like a ladder is the chemical basis for
development.
Each chain consists of pairs of chemical substances=bases (A-T & C-G). The
sequence of pairs provides the genetic instruction
Genes are segments of DNA along the length of the chromosome. Genes have
different lengths.
Small genetic variation between humans and other species and even less between
each individual.
DNA has the function of duplicating itself and that is the start for a zygote to
develop into a complex human being
Mitosis
The process by which a cell duplicates its
chromosomes and then divides into two
identical daughter cells. Fist it duplicates
the 46 chromosomes and these sets
move into an opposite direction and then
the division of two identical cells with 23
pairs of chromosome each are created.
, Developmental Psychology
Problem 1-The Birds and the Bees
Meiosis
The process by which a germ cell divides, producing gametes (sperm or ova) that each
contain half of the parent cell’s original complement of chromosomes; in humans, the
products of meiosis contain 23 chromosomes.
→During meiosis the duplicated adjacent chromosomes cross-over, transferring genes and
then continues with
dividing into two cells
of 46 chromosomes.
These cells divide
into two more cells
each that contain 23
single chromosomes.
Meiosis
All body cells reproduce themselves in
this way
To produce gametes (ovum-sperm)
Four genetically different haploid sex
cells (23 unpaired chromosomes)
Two divisions
Anaphase I: Homologue chromosomes
separate Anaphase II: sister chromatids
separate.
Independent assortment: Principle that each pair of chromosomes during meiosis
segregates independently of all other chromosome pairs. The result is that many different
combination of chromosomes can occur.
Monozygotic twins: The zygote that starts duplicating separates in two clusters of cells that
develop into two individuals. Identical genes.
Dizygotic twins: Result from release and fertilization of two ova by different sperm,
genetically they are more alike than ordinary siblings.
Genetic Inheritance
Allele: Alternative(two) forms of a gene that can appear at a particular site on a
chromosome, one inherited from the mother and one from the father.
Problem 1-The Birds and the Bees
Genetic foundations
Genotype: The genetic information that an individual inherits which determines our species
and influences the unique traits/characteristics.
Phenotype: The way one person’s genotype is expressed in observable or measurable
characteristics.
Gametes
The sex cells, sperm and ovum.
Sperm cell →release its genetic material + Ovum →release its genetic material = a new cell
nucleus= zygote.
Chromosomes
Nucleus contains 46 chromosomes (23 pairs, 22 autosomal, 1 pair sex chromosomes-X long-
Y-short). One member of each pair comes from the ovum and one from the sperm.
Chromosomes are made up of DNA (deoxyribonucleic acid).
DNA
A complex double-helix model that looks like a ladder is the chemical basis for
development.
Each chain consists of pairs of chemical substances=bases (A-T & C-G). The
sequence of pairs provides the genetic instruction
Genes are segments of DNA along the length of the chromosome. Genes have
different lengths.
Small genetic variation between humans and other species and even less between
each individual.
DNA has the function of duplicating itself and that is the start for a zygote to
develop into a complex human being
Mitosis
The process by which a cell duplicates its
chromosomes and then divides into two
identical daughter cells. Fist it duplicates
the 46 chromosomes and these sets
move into an opposite direction and then
the division of two identical cells with 23
pairs of chromosome each are created.
, Developmental Psychology
Problem 1-The Birds and the Bees
Meiosis
The process by which a germ cell divides, producing gametes (sperm or ova) that each
contain half of the parent cell’s original complement of chromosomes; in humans, the
products of meiosis contain 23 chromosomes.
→During meiosis the duplicated adjacent chromosomes cross-over, transferring genes and
then continues with
dividing into two cells
of 46 chromosomes.
These cells divide
into two more cells
each that contain 23
single chromosomes.
Meiosis
All body cells reproduce themselves in
this way
To produce gametes (ovum-sperm)
Four genetically different haploid sex
cells (23 unpaired chromosomes)
Two divisions
Anaphase I: Homologue chromosomes
separate Anaphase II: sister chromatids
separate.
Independent assortment: Principle that each pair of chromosomes during meiosis
segregates independently of all other chromosome pairs. The result is that many different
combination of chromosomes can occur.
Monozygotic twins: The zygote that starts duplicating separates in two clusters of cells that
develop into two individuals. Identical genes.
Dizygotic twins: Result from release and fertilization of two ova by different sperm,
genetically they are more alike than ordinary siblings.
Genetic Inheritance
Allele: Alternative(two) forms of a gene that can appear at a particular site on a
chromosome, one inherited from the mother and one from the father.
