Human Cells Flashcards
What is Cellular differentiation?
The process by which a cell develops more specialised functions by expressing the genes characteristic for that cell type.
What are somatic cells?
Body cells that are not Gametes
Where are somatic cells found and what do they make up?
Found throughout body
Make up different types of body tissue
How do somatic cells divide?
by mitosis
Somatic cells are diploid what does this mean?
contain 23 pairs of homologous chrmosomes
What are the 4 basic animal tissues?
Epithelial
Connective
Muscle
Nerve
Describe each of the 4 animal tissues?
Epithelial - cover the body surfaces and line the body cavities
Connective - supports, separates and binds other tissues
Muscle - made up of muscle cells, ability to contract
Nerve- main component of nervous system, senses stimuli and sends nerve impulses around the body
What are the three types of muscle tissue?
Skeletal
Cardiac
Smooth
What are the two main cell types in the nerve tissue?
Nerve cells
Glial cells
What are Stem cells?
Stem cells are unspecialised somatic cells that can divide to make copies of themselves or differentiate into specialised cells
What are the two types of stem cells?
Embryonic
Tissue
Describe Embryonic stem cells?
- come from inner cell mass of an early embryo
- can self-renew
- Can differentiate into all cell types of that organism(pluripotent)
Describe Tissue stem cells?
- can differentiate into cell types of the tissue they are found in
- involved in growth, repair and renewal of cells
- They are multipotent
What is differentiation?
Differentiation is when cells become specialised
Describe Differentiation?
- Unspecialised cells become adapted to perform a specific function
- therefore cells switch on or off particular gene
- Once a cell differentiates it expresses genes that produce proteins characteristic for that cell type
Why are cells specialised?
To conserve energy
division of labour
What is a germline cell?
A germline cell is a cell which can divide to produce Gametes
Where are germline cells found?
Ovaries and Testes
What are the different ways germline cells can divide?
Mitosis - forms two new diploid germline daughter cells
Meiosis - forms four new haploid gamete cells
What is a mutation?
A mutation is a change to the genetic code in a cell
How can a mutation in a germline cell be passed to offspring?
The cells divide to form gametes
Why are mutations in somatic cells not passed to offspring?
these cells divide to form new somatic cells
Define Cancer?
Cancer is an uncontrolled growth of abnormal cells
Define Tumour?
Cells which continue to divide to form a mass of abnormal cells
How are most cancers formed?
When series of mutations takes place in somatic cells
What do mutagenic agents do?
They increase the rate of mutations in cells
Name two Mutagenic agents?
Radiation
Carcinogenic chemicals
Describe Benign tumours?
- Form in an area of the body
- cells adhere to each other and remain in that area
- do not spread and are not classed as a cancer
Describe Malignant tumours?
- cells do not adhere to each other
- They can spread to other tissues and form secondary tumours
Where are chromosomes found?
In the nucleus
What do chromosomes contain ?
Genetic information which code for proteins
What are chromosomes made up of?
DNA (DEOXYRIBONUCLEIC ACID)
The sequence of genetic code determines what?
The genotype of an organism
Describe DNA?
- Twisted double helix
- double stranded
- built from subunits called nucleotides
A DNA nucleotide has 3 parts to it, name them?
Phosphate
Deoxyribose sugar
base
How is a sugar phosphate backbone formed?
The nucleotides join together between the deoxyribose sugar and the phosphate group of the next
What are the 4 DNA bases?
ADENINE(A)
THYMINE(T)
GUANINE(G)
CYTOSINE(C)
What do Weak hydrogen bonds do?
hold the two strands of DNA together
What does complementary base pair mean?
The bases will always pair up with in DNA
A - T
C - G
Describe the two ends of DNA strands?
A 3’ end with deoxyribose sugar at the end
A 5’ end with phosphate at the end
DNA strands will always run what to each other?
Antiparallel
DNA can do what ?
Control its own replication?
When does DNA replication take place?
Before Mitosis or Meiosis and cell division
DNA replication is described as what?
Semi conservative as each daughter molecule contains one strand from the original molecule and one newly synthesised strand
Describe stage 1 of DNA replication?
- molecule unwinds and unzips
- 2 template strands formed
- exposes bases of original DNA strands
Describe stage 2 of DNA replication?
- DNA nucleotides line up through complementary base pairing
Describe stage 3 of DNA replication?
-Hydrogen bonds form between base pairs
Describe stage 4 of DNA replication?
- DNA polymerase forms the sugar phosphate backbone at the 3’ end
Describe DNA Polymerase?
DNA polymerase replicates a dna strand precisely using DNA nucleotides
Needs a primer to start replication
can only add complementary nucleotides to the 3’ end
How are the two strands of DNA replicated differently?
leading strand is replicated continuously
lagging strand is replicated in fragments
what enzyme joins fragments produced in the lagging strand?
Ligase
What must be present for DNA replication to occur?
DNA template Free DNA nucleotides Primers ATP Enzymes
How is phenotype determined?
By the proteins produced as a result of gene expression
what does intra and extra cellular mean?
Intra cellular inside the cell
extra cellular outside the cell
The sequence of bases on the DNA is called what?
The genetic code
What is stage 1 of gene expression (Protein synthesis)?
Transcription - the genetic code is copied and a copy of it is carried on a strand of mRNA to a ribosome
What is stage 2 of gene expression (Protein synthesis)?
Translation - tRNA caries specific amino acids to the ribosome tRNA and mRNA pair up through complementary base pairing
Describe the structure of RNA
RNA is a nucleic acid
It is made up of nucleotides joined together by sugar phosphate bonding
What are the three types of RNA?
messenger - mRNA
Transfer - tRNA
Ribosomal -rNA
Describe the types of RNA
mRNA - Long single stranded chain that carries a copy of the genetic code from nucleus to ribosome.
tRNA - Carries specific amino acids to the ribosome
rNA - Ribosomes are made up of rRNA and protein subunits
What is a mutation?
A mutation is a change to the genetic structure of an organism?
How a re genetic disorders caused?
Changes to genes or chromosomes which result in proteins not being expressed or the proteins not functioning properly.
what are single gene mutations?
They change the sequence of nucleotides of the DNA
What is Bioinformatics?
Bioinformatics is the use of computer technology to identify DNA sequences
What is systematics?
Systematics is the comparison of the human genome sequence data that provides information on the evolutionary releationships and origins
What is PCR?
Polymerase chain reaction is a technique to amplify DNA outside the body.
This is the process of taking tiny samples of DNA and producing vast numbers of copies of it
What is a metabolic pathway?
A metabolic pathway is a sequence of enzyme controlled reactions where the products of one reaction can influence the next reaction in the pathway.
What are the two types of chemical reaction within a cell?
Anabolic - build up reactions
Catabolic breakdown reactions
How do enzymes speed up the rate of chemical reactions?
By lowering the activation energy in the reaction
What is an inhibitor?
An inhibitor is a molecule that reduces or stops enzyme activity
What is respiration?
Respiration is a metabolic pathway that releases energy by breaking down glucose it is a series of enzyme controlled reactions
How is ATP built up?
ATP is built up from ADP and phosphate by PHOSPHORYLATION
What is Phosphorylation?
Phosphorylation is when a phosphate group is added to a molecule making it more reactive
Where does the Citric acid Cylcle take place?
In the central matrix of the mitochondria
What is the electron transport chain?
A group of proteins attached to the inner membrane of the mitochondria
What is the final electron acceptor?
Oxygen, which combines with hydrogen ions and electrons to form water.
What does Phosphofructokinase do?
controls the phosphorylation of the irreversible stage of glycolysis
What are the 3 types of muscle tissue?
Skeletal
Cardiac
Smooth
What are the 4 types of tissue?
Epithelial
Connective
Muscle
Nerve
What are three types of connective tissue?
Bone
Blood
Cartilage
Explain Cellular differentiation?
Cellular differentiation is the process by which a cell develops more specialised functions by expressing the genes characteristic of that type of cell
What are somatic cells?
Body cells that are not gametes
Somatic cells are said to be what?
Diploid
Somatic cells divide by what?
Mitosis to produce genetically identical diploid daughter cells
Give an example of epithelial tissue
Skin
Skeletal muscle tissue is involved in what?
Voluntary movements
Nerve tissue is the main component of what?
the nervous system
Smooth muscle is found where?
digestive tract, bladder and arteries
Smooth muscle tissue is involved in what?
Involuntary movements such as peristalsis
Cardiac muscle is found where?
The heart
There are two main cell types in the nerve tissue what are they?
Nerve cells and Gial Cells
A nerve cell does what?
Senses stimuli and sends nerve impulses around the body through the nervous system
