17.1 Fertilization
Fertilization occurs when an egg and a sperm join together forming a zygote which is the first cell of a new individual.
The egg has to go through some changes to prevent any more sperm from entering.
17.2 Pre-Embryonic and Embryonic Development
The 4 main processes for development are cleavage, growth, morphogenesis and differentiation.
Pre-embryonic development occurs only during the first week.
Embryonic development starts at the second week and lasts until the end pf the second month.
The first organ system that is visually evident is the nervous system, this happens in the third week. And the heart starts developing during this week.
Sometime in the sixth to eighth weeks the embryo becomes easier to recognize as a human being.
17.3 Fetal Development
The blood of the fetus and the blood of the mother never mix because exchange occurs across the villi.
At three to four months in fetal development hair and fingernails are starting to appear and you can determine the sex of the baby.
At five to seven months you can feel the baby moving and its possible that if the baby had to be born now it could still survive.
Towards the end of development the baby is about 20.5 inches long weighing about 7.5 lbs. Also most of the time the baby will get turned around so that the head is facing towards the cervix.
17.4 Pregnancy and Birth
During pregnancy women go through so big changes with their bodies, for example gaining weight and physiological changes.
Actual birthing is said to begin when uterine contractions occur consistently for 15-20 minutes and last 40 seconds or longer. The 3 stages of birth are shown below
17.5 Development After BirthThe four stages of life consist of infancy, childhood, adolescence and adulthood.
With aging comes loose skin, women going through menopause and cardiovascular disorders along with other things.
Maintaining a healthy life style can make aging easier.
Chapter 18- Patterns of Chromosome Inheritance
18.1 Chromosomes and the Cell Cycle
We have a total of 46 chromosomes equaling 23 pairs, 22 of these pairs are automsomes and 1 pair is the sex chromosome.
Mitosis makes sure that all the cells have 46 chromosomes.
The cell cycle consists of 2 parts interphase and cell division.
The picture below shows the cell cycle
18.2 MitosisMitosis is duplication division- the dividing cell and the new cell are genetically identical.
Duplication of the centrosome is an important part that occurs during mitosis.
There are 4 phases of mitosis; prophase, metaphase, anaphase and telophase.
Mitosis is important because it helps with growth and tissue repair.
18.3 Meiosis
Meiosis is known as the reduction division and consists of 2 divisions meiosis I and meiosis II.
In meiosis I the homologous chromosomes line up beside each other.
In meiosis II the sister chromatids separate, becoming daughter chromosomes.
Meiosis is the production of the egg and sperm.
18.4 Comparison of Meiosis and Mitosis
Mitosis takes place throughout growth and repair in all the cells whereas meiosis takes place only in the reproductive organs. Meiosis requires 2 nuclear divisions whereas mitosis only requires 1.
Males produce 400 million sperm a day and this starts after puberty.
In female 1 egg is produced a month.
18.5 Chromosome Inheritance
People can be born with too few or too many sex chromosomes or autosomes when this happens it is most likely due to nondisjunction.
Down syndrome is usually caused by chromosome 21 because the egg has 2 copies instead of 1.
Some chromosomal mutations are shown below:
Deletion- one end of a chromosome breaks off or 2 simultaneous breaks lead to loss of an internal segment.
Duplication- chromosomal segment occurs more than once.
Translocation- chromosome segment moving from one to another.
Chapter 19- Cancer
19.1 Cancer Cells
A cellular disease known as cancer share characteristics that separate them from normal cells.
Cancer cells can replicate over and over, they have an abnormal nuclei and don’t have differentiation.
Cancer is genetic.
Oncogenes become cancer causing genes when proto-oncogenes mutate.
The different types of cancer are leukemia which is cancer of the blood, sarcomas which is cancer in the muscle and connective tissue and carcinomas which is cancer in the epithelial tissues.
Cancer can be in any part of the body however some organs are more susceptible.
19.2 Causes and Prevention of Cancer
Radiation, organic chemicals and viruses can cause cancer and of course so can genetics.
19.3 Diagnosis of Cancer
An easy way to remember 7 warning signs for cancer are CAUTION: a Change in bladder or bowel habits, A sore that does not heal, Unusual bleeding or discharge, Thickening or lump in breast or elsewhere, Indigestion or difficulty in swallowing, Obvious change in wart or mole, Nagging cough or hoarseness.
Women should perform self tests at home for breast cancer and males should check for testicular cancer, along with routine check ups with your doctor.
Other ways to detect cancer are genetics tests and tumor marker tests which are blood tests for antigens/antibodies.
19.4 Treatment of Cancer
Surgery, radiation and radiation therapy are all types of treatment for cancer.
There are some newer treatments for cancer like immunotherapy which is injecting immune cells that have been genetically engineered to fight the tumors antigens and p53 gene therapy which triggers cell death only in the affected cancer cells.
Chapter 20- Patterns of Genetic Inheritance
20.1 Genotype and Phenotype
The genes of a person are known as genotype and phenotype is the physical characteristics associated with these.
Alleles are another form of a gene and occur at the same locus on homologous chromosomes.
To help understand genotype and phenotype see the picture below:
20.2 One- and Two- Trait InheritanceIn one- trait crosses a person has 2 alleles for every trait and a gamete has one for every trait. By knowing the genotype and the gametes a parent could figure the chances of their child having a certain genotype and phenotype.
The Punnett Square can help you to determine the chances of your child having a certain phenotype and genotype by using sperm and egg, lining them up in a square and all the chances occurring inside the square. (eggs vertically and sperm horizontally or the other way around).
In two- trait crossing 4 gamete types are possible if the person is heterozygous for 2 traits.
Autosomal recessive disorder is when the child is affected but neither one of the parents are, the parents can be the carrier but not be affected. In autosomal dominant disorder the child can be unaffected while the parents are affected. The child can receive 2 recessive alleles and be unaffected.
Some autosomal recessive disorders are cystic fibrosis and sickle cell disease and some autosomal dominant disorders are marfan syndrome and Huntington disease.
20.3 Beyond Simple Inheritance Patterns
Alleles are not just recessive or dominant in some parts of inheritance.
Polygenic traits are ruled by several sets of alleles and can be located on many different pairs of chromosomes.
Environmental influences can have more of an affect on multifactorial disorders.
A gene can exist in several allelic forms when a trait is controlled by multiple alleles.
20.4 Sex Linked Inheritance
Sex linked traits are traits controlled by genes on the sex chromosomes, an x-linked is allele on an x chromosome and a y-linked is an allele on a y chromosome.
Being color blind and having muscular dystrophy are both x-linked recessive disorders. Males tend to have these characteristics more than females.
Chapter 21- DNA Biology and Technology
21.1 DNA and RNA Structure and Function
DNA is the genetic material that is found in the nucleus of the chromosomes.
DNA is a double helix or 2 strands that spiral around each other.
DNA has to replicate to be passed on.
A picture of DNA replication is shown below:
RNA consists of nucleotides that have the sugar ribose, the 4 nucleotides that make up RNA have adenine, uracil, cytosine and guanine for its bases.RNA is only single stranded and helps DNA for protein synthesis to occur.
3 types of RNA are Ribosomal RNA where it joins with proteins made in the cytoplasm to make subunits of ribsomes, messenger RNA which carries genetic information to the ribosomes from the DNA and transfer RNA where it transfers amino acids to the ribosomes.
21.2 Gene Expression
Amino acids make up proteins and 20 different amino acids can be found in proteins.
2 steps in gene expression are transcription and translation. All 3 types of RNA are made by transcription.
Controlling of gene expression is transcriptional control which occurs in the nucleus, posttranscriptional control which also takes place in the nucleus, translational control and posttranslational control where both take place in the cytoplasm.
21.3 Genomics
The study of genomes is known as genomics. Genome size does not relate to the number of genes.
Comparing genomes has helped to find out how species have evolved.
The study of structure, function and interaction of cellular proteins is known as proteomics.
A persons genome can be changed by gene therapy. Gene therapy can be used to treat disorders and diseases.
21.4 DNA Technology
To produce genetically identical copies of DNA is cloning. Recombinant DNA contains DNA from 2 or more different sources.
Cloning a human gene is shown below:
The polymerase chain reaction can work if only small pieces of DNA are needed. It can create copies of a DNA.
DNA fingerprinting has led to being able to convict criminals and identify bodies.
Biotechnology products are made by genetically engineering plants, animals and bacteria. Plants have been able to make human hormones and antibodies. Animals have been able to make pharmaceuticals.
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