2° Bimonthy resume by Paulina Quezada Reyes M1226

THE CELL AND INHERITANCE:
Mendel`s work showed that genes exit. But scientists in the early twentieth century did not know what structures in cells contained genes. Chromosome pairs play in inheritance, the relationship between chromosomes and genes is the meiosis. Meiosis is the process by which the number of chromosomes is reduced by half to form sex cells sperm and eggs. During the meiosis, the chromosome pairs separate and are distributed two different cells. The resulting sex cells have only half as many chromosomes as the other cells in the organism. A punnett square is actually a way to show the events that eccur of meiosis when the chromosome pairs separate and go into two different sex cells, so do the alleles carried on each chromosome. One allele from each pair goes to each sex cell. Chromosomes are made up of many genes joined together like beads on a string.

THE DNA CONNECTION:
The genetic code. The main function on genes is to control the production of proteins in an organism`s cells proteins help to determinate the size, shape, color and many traits of an organism. The order of the nitrogen bases along a gene forms a genetic code that specifics what type of protein will be produced. During protein synthesis the cell uses information from a gene on a chromosome to produce a specific protein. Messenger RNA copies the coded message from the DNA in the nucleus . transfer RNA carries amino acids to the ribosome a mutation can cause a cell to produce an incorrect protein during protein synthesis . as a result the organism`s trait or phenotype.

MODERN GENETIC:
Some human traits are controlled by single genes with two alleles and others by single genes with multiple alleles. Still other traits are controlled by many genes that act together. Multiple alleles three or more forms of a gene that code for a single trait . the sex chromosomes are one of the 23 pairs of chromosomes in each body cell . the sex chromosomes carry genes that determine whether a person is male or female. They also carry genes that determine other traits.

CAUSES OF GENETIC DISOIDERS:
Some genetic disorders are caused by mutations in the DNA of genes. Other disorder are caused by changed in the overall structure or number of chromosomes. Common genetic disorders: cystic figrosis, sickle cell disease, hemophilia, down syndrome. Selective breeding cloning and genetic engineering are three methods for developing organisms with desirable traits. Darwin´s important observations included the diversity of living things, the remains of ancient organisms and the characteristics of organisms on the Galapagos islands, a species is a group of similar organisms.

A FOSSIL:
Is the preserved remains or traces of an organism that lived in the past. Darwin hypothesized the species gradually changed over many generations and became better adapted to the new conditions. Scientists have cobined the evidence from DNA protein structure fossils, early development and body structure to determine the evolutionary relationships among species.

VIRUS:
Is a tiny, nonliving particle that invades and then multiplies inside a living a cell. The only way in which viruses are like organisms is that they can multiply. All viruses have two basic parts: a protein coat that protects the virus and an inner core made of genetic material.

BACTERIA:
Are prokaryotes. The genetic material in their cells is not contained in a nucleus flawellum a long whiplike structure that a helps cell move.

FUNGI:
Fungi are eukaryotes that have cell walls, are heterothrops that feed by absorbing their food, and use spores to produce. Hyphae are the branching threadlike tubes that make up the bodies of multicellular fungi.

THE PLANT KINGDOM:
Nearly all plants are autotrophs, organisms that produce their own food. All plants are eukaryotes that contain many cells. In addition , all plant cells are surrounded by cell walls . adaptations for living on land, they must have ways for plants to survive on land , they must have ways to obtain water and other nutrients from their surroundings, retain water, transport materials in their bodies, support their bodies, and reproduce. Plants without seeds there are three major groups of nonvascular plants: mosses, liverworts, and hornworts. These low-growing plants live in moist areas where they can absorb water an other nutrients directly from their environment. Characteristics of seedless vascular plants. Ferns, club mosses, and horsetails have true vascular tissue, and they do not produce seeds. Instead of seeds, these plants reproduce releasing spores.

THE CHARACTERISTICS OF SEED PLANTS:
Seed plants share two important characteristics they have vascular tissue, and they use pollen and seeds to reproduce. Inside seed is a partially developed plant. Ifassed lands in area where conditions are favorable, the plant sprouts out of the seeds and begins to grow.

GYMNOSPERMS AND ANGYOSPERMS:
Every gymnosperm produces naked seeds. In addition many gymnosperms have needle like or scalelike leaves and deep growing root systems. Types of gymnosperms: cycads, conifers, ginkgoes, gnetophytes, reproduction first, pollen fast from a male cone onto a female con. In time,a sperm cell and egg cell join together in an ovule on the female cone.

PLANT RESPONSES AND GROWTH:
Touch, light and gravity are three important stimul which plants show growth responses, or tropisms. Plant responses to seasonal changes include photoperiodism and dormancy.

STRUCTURE OF ANIMALS:
The cells of most animals are organized into higher levels of structure, including tissues, organs and systems the major functions of animals are to obtain food and oxygen, keep internal conditions stable, move and reproduce.

ANIMAL SYMMETRY:
This balanced arrangement of parts, called symmetry, is characteristic of many animals.

SPONGES AND CNIDARIANS:
Sponges are invertebrate animals that usually have no body symmetry and never have tissues or organs.

WORMS:
Biologists classify worms into three major phylaflatworms, roundworms, and segmented worms. Flatworms are flat and as soft as jelly.

MOLLUSKS:
In additionto a soft body often covered by a shell a mollusk has a thin layer of tissue called a mantle that covers its internal organs, and on organ called a foot.

ARTHROPODS:
The major groups of arthropods are crustaceans, arachinds, centipedes and millipedes, and insects. Arthropods are invertebrates that have an external skeleton, a segmented body, and jointed attachments called appendages.

INSECTS:
Insects are arthropods with three body sections six legs, one pair of antennae, and and usually one or two pairs of wings. An insects mouthparts are adapted for a highly specific way of getting food. Each insect species undergoes either complete metamorphosis insects play key roles in food chains because of the many different ways that they obtain food and then become food fair other animals.