Human Cells

What are somatic cells?
Somatic cells are body cells that are NOT gametes
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What is the term used to describe somatic cells and how many pairs of chromosomes do they have?
Somatic cells are described as being diploid, meaning they contain 23 pairs of homologous chromosomes
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How do somatic cells divide?
Somatic cells divide by mitosis
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What are the four types of tissues and desribe them?
Epithelial- cover bodys surfaces, connective- supports,separates and binds to other tissues, muscle-have the ability to contract and nerve-sends nerve impulses around the body
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What are stem cells?
Stem cells are unspecialised cells that have the ability to differentiate into specialised cells
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What are the two types of stem cells?
Embryonic and Tissue stem cells
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What are embryonic stem cells?
Embryonic stem cells can differentiate into all cell types and are described as being pluripotent and they can self-renew.
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What are tissue stem cells?
Tissue stem cells can only differentiate into the cell types of the tissue that they are found in and are described as being multipotent
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What is differentiation?
Differentiation is the process where cells become specialised
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How does differentiation work?
Cells switch off or on certain genes
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Why is differentiation important?
Differentiation is important because it conserves energy.
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What is a germline cell?
A germline cell divided to produce gametes (sex cells)
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Where are germline cells found and how do they divide?
Germline cells are found in the ovaries in females and in the testes in females. They divide by mitosis and meiosis
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What is a mutation?
A mutation is a random change to the genetic material
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What type of cell is a mutation most lethal?
A mutation in a germline cell is more lethal as it can be passed on to offspring
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What have stem cells been used to study?
Cell growth, gene manipulation and differentiation
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Why can stem cells be used as model cells?
because they are cells that have similar biological characteristics to the cells that are needed to research
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Due to being model cells, stem cells can be used to study what?
The effects of new drugs and diseases and genetic disorders
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What are the therapeutic uses of stem cells?
Bone marrow transplant, skin grafts and cornea repairs
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What are the ethics surrounding stem cells?
heavily regulated by UK laws and must be approved by a regulatory body and a license . They cant be used once they are older than 14 days.
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What is cancer?
Cancer is an uncontrolled growth of abnormal cells
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How do cancer cells develop?
Cancer cells do not respond to the usual regulatory signals and chemical messengers
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What is a tumour?
A tumour is a mass of abnormal cells
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What are two types of mutagenic agents?
UV radiation and carcinogenic chemicals
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What are the two types of tumours?
Benign and malignant
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What are benign tumours?
benign tumours adhere to each other and do not spread
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What are malignant tumours?
Malignant tumours do not adhere to each other and spread around the body to form secondary tumours
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Describe the structure of DNA
DNA is double stranded and is described as being a double helix. Dna is built from subunits called nucleotides
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What are the 3 parts of a nucleotide?
Base, phosphate and deoxyribose sugar
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What are the four DNA bases?
Adenine, Thymine, Cytosine and Guanine
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explain the 5' and 3'end
The 3' end contains a deoxyribose sugar at the end and the 5'end contains a phosphate at the end. The strands are ANTIPARALLEL
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When does DNA replication take place?
DNA replication takes place before mitosis and meiosis
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Why is DNA replication described as being semi conservative?
Because it contains one strand from the original molecule and one newly synthesised strand
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What are the stages of DNA replication?
1. DNA molecule unwinds and unzips (hydrogen bonds break) 2. Free DNA nucleotides line up through complementary base pairing 3. Hydrogen bonds form between strands 4. DNA polymerase forms the sugar phosphate backbone.
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What is the function of DNA polymerase in DNA replication?
DNA polymerase adds nucleotides to the 3' end of the strand
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Explain how the two strands are replicated and the role of ligase?
the leading strand is replicated continuosuly and the lagging strand is replicated in fragments. The enzyme ligase joins the fragments in the lagging strand together
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What are the 5 requirements for DNA replication?
DNA template, Free DNA nucleotides, Primers, ATP and appropriate enzymes
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Card 2

Front

What is the term used to describe somatic cells and how many pairs of chromosomes do they have?

Back

Somatic cells are described as being diploid, meaning they contain 23 pairs of homologous chromosomes

Card 3

Front

How do somatic cells divide?

Back

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Card 4

Front

What are the four types of tissues and desribe them?

Back

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Card 5

Front

What are stem cells?

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